I have 92 ply Voyager turns over fine

What you need is a regular scanner that will access all of the computers. Most auto parts stores that read codes for you for free are using simple code readers. Code readers take two minutes to learn how to use. To learn the original Chrysler DRB3 I attended a two-day-long class. Comparing a code reader to a scanner is like comparing a computer mouse to the entire computer system. It doesn't do much.

The code readers I've seen only access the Engine Computer. They will not read Anti-lock Brake computer codes, Transmission Computer codes, Air Bag Computers, and things like that. I haven't heard of a government law that says you can't erase certain emissions codes. That would not make sense, but then again, politicians don't have any common sense. In fact, every problem they say we have and only they can fix was caused by the laws they passed previously. You NEED to be able to erase a code so if it comes back you'll know the problem is not fixed. You also need to know when a new problem is detected, and many self-tests won't run and many new problems won't be detected when certain other codes are already in memory.

In the past engine codes always erased by disconnecting the battery. That also erased fuel-trim data but those tables got rebuilt without you even noticing once you started driving it again. The codes in some ABS Computers could not be erased without a scanner. They would still be there when you reconnected the battery. Engine codes also used to erase automatically after 50 engine starts if the problem didn't act up again. I don't know if that's the case with a 2003 model but I have no reason to think it's different.

When they said their tester doesn't "read the problem", it sounds like what they're referring to is that difference between a scanner and a code reader. The code reader just shows the code number for the reason the Engine Computer is not happy. A scanner will show the information the computer is receiving to make those decisions to set codes and that it uses to adjust the fuel / air mixture and spark timing. You will see pages of sensor values and the information those values represent. It will show which switches are on and off, which relays it has turned on and off, and scanners are "bidirectional", meaning you can control stuff from its keyboard. You can operate the radiator fan and emissions solenoid circuits to allow you to take voltage readings and do other troubleshooting.

The scanner will display the speed sensor readings in real time. If you see one staying on "0", you'll know which circuit to diagnose.

As for welding on the vehicle, there's two schools of thought. The reason most people say to disconnect the battery is so there's no 12 volts feeding the computer memory circuits. Even with the ignition switch off, there's a small amount of circuitry still active in the computers. The radio is an easy-to-understand example. It maintains the clock time and the station presets with the ignition switch off. The thinking is those circuits will be dead so any voltage spikes that are magnetically "induced" into the wiring will not enter the computers and cause damage.

From my extensive tv / vcr repair background, I find the logic hard to agree with. Those voltage spikes that might be created are going to enter the computers on some sensor wires anyway, and that's where they could theoretically cause damage. With the memory circuits still powered up, those circuits could start to act on those spikes as though they were signals coming in from the various sensors. The problem with that theory is those circuits are able to filter out those spikes and ignore them when the computers are operating. They're even more able to block those voltage spikes when they're turned off.

The other problem I have is that the battery is so extremely huge electrically compared to those little voltage spikes that it holds the voltage steady at 12 volts and absorbs those spikes. With the battery disconnected there's nothing to hold the voltage to safe level. You have to first understand the two important laws of physics that makes an alternator work. 1) When you pass an electrical current through a wire, that sets up a magnetic field around it. 2) When you move a wire through a magnetic field, that field "induces" or CAUSES a current to want to flow in it. For the first one, the field strength is weak but if you coil that wire up, each loop adds to the strength. Remember making an electromagnet in science class with a nail, wire, and battery, and picking up paper clips with it? That's the first half of an alternator.

When you weld on the car, current is flowing between the electrode and ground clamp. Wherever it flows, a magnetic field is created. If that's through part of the frame rail and there's a wire harness laying alongside it, that magnetic field will induce a voltage into those wires. If those wires go to a tail light bulb, the voltage induced is not nearly strong enough to cause the bulbs to light up. If those wires are for a computer sensor, it is very unlikely the voltage induced will be anywhere near as high as the signal voltages those sensors normally produce. The parts of the computers that act on those sensor voltages are not functioning when the ignition switch is turned off so what difference does it make if a small voltage spike shows up there?

The voltage spikes are going to be created whether the battery is disconnected or not. For the people who think a computer is going to be damaged, the only way to isolate it from those spikes is to unplug every computer on the vehicle, and by the late '90s, that could be dozens of computer modules. I've never heard of anyone doing that.

I have the Chrysler DRB3 because all I will ever own are older Chryslers. Because it's a newer version, it only works back to 1998 models by itself. With a small plug-in card it will work back to '94 models and it will do OBD2 emissions-related diagnostics on all car brands sold in the U.S. I have another card that lets it work on '83 - '93 Chryslers. I bought this as a set through the dealer I used to work for. You can find them on eBay and you can buy them directly from the manufacturer but at a much higher cost. The cost is prohibitive for you though because for what you would spend, you can pay your mechanic to diagnose a lot of problems.

I also have the older Chrysler DRB2 but that only works on '95 and older models. You can find those very reasonably-priced on eBay. I have a Monitor 4000 which is very similar to the DRB2 and is made by the same manufacturer. The aftermarket scanners never do quite as much as the manufacturer's stuff, but in this case, I can work on Chryslers, GMs, and Fords with one cartridge. Another cartridge is strictly for the Chrysler A604 automatic transmission, and I have another one for anti-lock brakes, but I've never used it yet.

Snapon makes a number of very nice scanners but they are extremely proud of their products and charge accordingly for them. A lot of people have the Genesis and like it but I've only used one a little and I'm not that familiar with it.

If you do a search for "automotive scanner" on eBay, you'll see all kinds listed, and you'll learn a lot about them from reading the descriptions. The disadvantage to my DRB3 and the Genesis, and others is they have to be updated periodically. That isn't necessary for personal use but mine was just done by a former student who works at another dealership. The disadvantage of the older scanners, at least as far as shops are concerned, is you have to buy new cartridges all the time. With my Monitor 4000, I bought used cartridges that were two to four years old from the guys on the tool trucks. They traded them in from guys who wanted the very latest ones.

One of those that needs new cartridges all the time is the Snapon MT2500. We call that one the "red brick" because that's what it looks like. I used that one a lot at school but I never liked it after becoming familiar with the DRB3. I'm sure you'll find a lot of those on eBay real cheap along with lots of cartridges. They were around since the '90s and most mechanics have upgraded to something newer. They use two cartridges at once. One of them will walk you through troubleshooting steps with wire colors and test points, I'm told. I never let my students rely on that. I taught them to understand how the circuits work and how to read wiring diagrams.

You can also find a lot of simple code readers on eBay. Personally I wouldn't waste my money on them. They work perfectly fine, but Chrysler makes reading codes so much easier than any other manufacturer. The readers won't tell you anything you can't learn from cycling the ignition switch and reading the code numbers from the service manual.

As for cost, you'll be able to judge that better after looking at a lot of eBay listings. My DRB3 kit listed for around $6500.00 about five years ago but since they still like me at my former dealership, and I fix a lot of radios for them, they charged me less than $4000.00. Twelve years ago when I bought one for my Automotive program, the three "Super Cards" that let it work on older and other models cost around $440.00 each. I haven't looked at those on eBay in a long time but they had used ones all the time for less than half the cost of new ones. My DRB3 kit included six cables to cover all Chrysler products, but you still have to buy the Super Card for some cars. The replacement OBD2 cable costs over $100.00 but you can find new ones on eBay for less than 20 bucks.

I just did a search for the MT2500 on eBay, and found them from $285.00 to $800.00 with a big variety of included cables and cartridges. Also consider watching for auctions when a local car dealer or repair shop goes out of business. The problem there is you'll be bidding against other people who know what the stuff is worth to a business so you'll likely end up paying more than necessary.

Did a search for the DRB3 too but they're still in high demand and bringing high prices.

To get to the Body Computer, you have to remove the "knee blocker". That's the panel under the steering column. The parking brake release linkage is hooked to the handle. That does not have to be disconnected.

When the panel is off, you'll see the connectors for the computer at the far right side of the opening. There's one or two screws to remove, then it slides to the left to remove it.

The input speed sensor is nearest the engine. It reads the rotational speed of the torque converter. The output speed sensor reads the rotational speed of the ring gear in the differential so it will be further to the driver's side. It's on the front, halfway between the shift lever and the side cover.

Can't be of much help with speaker sizes because I always stuck with factory original stuff. I just shipped out two with a radio yesterday that I repaired. They were the front speakers for a 2000 Caravan and they fit perfectly in my much older '88 Grand Caravan to test-run them.

You won't find any aftermarket speakers that will bolt right in. The diameters and the number and spacing of the screw holes will be a lot different. If I understand correctly, you are looking for a plug that will let you connect different speakers to the factory connectors. If that's right, head to a salvage yard and snip some off the speakers. The ones I just sent out had two-wire connectors that could be slid off by pressing down a little lock tab. The wires were only an inch long but that would be enough to solder to the new speakers. Use some RTV gasket sealer to glue anything that could vibrate and cause an irritating noise.

For a real nice upgrade, look for a similar vehicle with the Infinity system. I'm not sure if they still offered it in on '03. My '88 has it. They used little amplifiers on the speakers, and they had four-wire connectors. A lot of the newer models used a remote amplifier, and the speakers were the normal two-wire type. The extra two wires are for the 12 volt feed and ground wires for the amplifiers.

The nice thing about Chrysler radios is they all run speakers directly so they all interchange. When Fords or GMs have a remote amp, those are needed with those radios, otherwise there won't be enough volume. Chrysler amps do not increase volume or power. They only modify the tone response for the shape of the vehicle. That way one model radio can be used in many vehicle models. GM has dozens of different radio model numbers every year that all look the same.

The Infinity radios put out less bass than normal. It is made up with the amp(s). If you install Infinity amplified speakers and use your standard radio, you'll have lots of bass and you'll need to turn it down to sound normal. If you install an Infinity radio and use standard speakers, the bass will be too low unless you turn it way up.

I really hate the rude loud thumping radios some kids install. I listen mostly to talk radio but when I play cds, I want to hear clean crisp high notes. The low-end standard radios just give you something to listen to. The Infinity systems give you something to enjoy.

If you don't have one now, look for a cd / cassette combo radio even if you don't have cassettes. Most of those radios were built by Mitsubishi and are very high quality. The supplier number on the model sticker is 28046. Most of the high-end cd-only radios were built by Alpine. Those have more problems and I can't get service manuals for their products.

If you add Infinity speaker with the amps bolted onto them, you'll have to run power and ground wires to them. Those get their power through a relay turned on by the radio. I can walk you through that if you go that route. If you use a remote amplifier, that gets pretty involved because you'll have to run 8 speaker wires from the radio to the amp, and 8 speaker wires from the amp to the speakers, a power and ground wire, and the turn-on wire from the radio. I don't know what's involved with removing that wire harness from another vehicle. You might get one long harness to make the modification easy, or there might be wires running all over the place.

Don't be terribly concerned with part numbers on the speakers. The number you order from the dealer can have a different number on the speaker and the box it came in. What's important is the application it came from. Most of them are two-way speakers with a crossover network bolted to them.

How is the radio hooked up now? Most people cut the original plug off the harness then splice the new radio's plug to the vehicle's wires. That makes it miserable for the next guy who wants to put an original radio back in. The best way is to buy an adapter harness. Some are offered by manufacturers that plug directly into the new radio and the harness. The more common ones just plug into the vehicle's connector, then you have to splice the wires to the new radio's connector. I've made adapter harnesses out of the female connectors from old radios that I've scrapped out. I can build those on the bench where it's easier to work, then I just plug 'em in. That worked well with the older two 7-pin connectors because a lot of those just unsnapped from the radio with no desoldering needed. With the newer 22-pin plugs you'll have to unsolder a connector from a radio. It would be a lot easier to just buy the right connector from Best Buy, and it will have the wires already on it.

Look behind the right front kick panel for the amp. A Chrysler amp can't deliver enough power to destroy speakers. It won't increase volume. It just provides tone conditioning. Basically they put out the same volume level as what comes in from the radio. That's why any Chrysler radio will run speakers directly or through an amp.

Aftermarket amplifiers DO increase volume and power. They are meant to be used with line-level outputs from radios with that feature. Line level is still controlled by the radio's volume control but it has to be amplified to run a speaker. If you use the speaker outputs on an aftermarket radio or any Chrysler radio, and run it through an aftermarket amplifier, the sound will be distorted and garbled even if you turn the volume down real low because the amp's input circuit is being overloaded. It isn't designed to process such large signal voltages.

As far as blowing speakers, it doesn't matter what you drive them with, a radio or an amplifier; both are designed to deliver the right power to run them. It's when you have an aftermarket amp capable of way more power than the speakers can handle that you have to worry. That is out of my area of expertise. I never got involved with anything aftermarket since I installed an aftermarket cassette player in the '70s.

If you find little speakers on the "A" pillars just above the outside mirrors, that was part of the Infinity system. The cutouts should already be in the door trim panels even if there's no speakers there. I helped a friend rebuild a few smashed Dodge trucks with the Infinity systems, and they sound really nice. I can hear the violins and snare drums through those little speakers.

To learn more, I would head to one of the pick-your-own-parts salvage yards and take some trucks apart. I think you will find the wire connectors are there in the "A" pillars taped up if they weren't used. If they're not, you will want to pull those wire harnesses out to add them to your truck. If you live anywhere between Ohio and southern Georgia, do a search for "Pull-A-Part". That is a real nice chain of yards where you pay your buck, throw your tool box into one of their wheel barrows, and you can spend all day there. Parts are very inexpensive and the employees and customers are real friendly. I bought a bunch of Intrepid amplifiers with wire harnesses there a few years ago for 20 bucks each.

I've never done this kind of modification. Installing the switches isn't the problem. I suspect you'll find many of the wires already run. It's the Body Computer you have to look at. What I would do is visit the dealer's parts department and have them look up the part number for it. If they ask you "with or without power locks, ... With or without power mirrors", etc, that will tell you the right computer is needed. Ask for the part number for the computer that matches what you want to install, then look for that one in a salvage yard.

If you they don't ask those questions, that implies the computer will "poll" the various circuits and self-program itself either when you turn on the ignition switch or when you reconnect the battery, or those things have to be activated with a scanner. My guess is you can just pop in a used computer and it will work because it would still have worked in the truck it was in when the battery was reconnected. It won't know it got transplanted into a different truck.

If a new coil failed, I'd expect to find it's an aftermarket replacement. Quality varies among manufacturers. For a no-start, monitor the voltage on the feed wire to the coil, any injector, or either small wire on the back of the alternator. That wire is usually dark green / orange. You should see 12 volts for one second after turning on the ignition switch. What's important is if that voltage comes back during cranking. If it does not, suspect the crankshaft position sensor or the camshaft position sensor. If it does show up, then diagnose the no-spark or no fuel pressure issue.

Discussing two different vehicles is confusing. If the Voyager has the A604 4-speed transmission, I doubt you'll find a shift kit for it. The operating characteristics are part of the programming in the computer. It knows the volume of fluid it takes to apply each clutch pack, and it continually updates the shift schedules and clutch-apply overlap to maintain a smooth solid shift as those plates wear down. There is no accumulator to soften the clutch application like we had in the hydraulically-controlled 904 and 727. The shift feel is controlled by pulsing the appropriate solenoids rapidly on and off to control and slow down fluid flow. That's the ratcheting noise you hear when you shift out of park.

If you have the 3-speed hydraulically-controlled transmission, those are so tough already that there's nothing you're going to do to extend its life. I have one in my '88 Grand Caravan daily driver, and I regularly pull an enclosed tandem axle trailer that's bigger and heavier than the van. I changed the fluid and filter once in its life only because the $3.50 side cover rusted out and was leaking at around 85,000 miles. It has over 238,000 miles now.

If you're talking about a shift kit for the truck, I don't know what's available. The weak point seemed to be the overdrive unit years ago. It was an add-on that replaced the tail housing. Once redesigned parts were made available we stopped hearing about problems. I don't know much about the newer truck transmissions. There are some computer controls but I think they're still mostly hydraulically-controlled.

The slippage you're referring to is anticipated when they designed the transmission and is very minimal. The worst problems are from severe overheating when people rock the vehicle back and forth trying to get unstuck from snow. Besides that, it's usually the lip seals that get hard with age and crack. That leads to internal fluid leakage and insufficient pressure on the clutch plates. That's where the excessive slippage comes from. When you take one apart that has been slipping, the fiber clutch plates are worn down as you would expect, but the steel plates are scorched too and the lip seals crack and crumble when you try to remove them. That means the slippage and wear wasn't caused by normal shift cycles. It was caused by the hardened seals. A shift kit won't help that.

Most professionals aren't big fans of chemicals that are designed to fix things, but you might look at adding a can of seal conditioner to the transmission fluid. That is supposed to help keep the seals rubbery and pliable.

As for the exhaust, the engine has to do work to push the exhaust out and anything that makes that easier will result in better fuel mileage. There is a point of diminishing return though. If you look at the huge pipes on a Cummins diesel, that is what is needed to get the exhaust out efficiently at any speed. The same is true on gas engines. Some vehicles come with a 2 1/4" exhaust pipe. The same model with a smaller engine may come with a 2" system to save a little money. The manufacturers are extremely competitive and if going to an exhaust system that was a puny 1/4" larger in diameter would get one more horsepower or one more mile per gallon that they could advertise, you can be sure they would do it. Headers and dual exhaust are options for people who have done other things to increase horsepower. Then the exhaust system becomes the weak link in the chain, so to speak, and is the biggest restriction to air flow in and out of the engine.

The two biggest factors in fuel consumption is friction and wind resistance. It takes a certain number of BTUs to move the truck. To lessen friction you have to lighten the vehicle. The designers already spend a lot of time in the wind tunnel so there's not much you're going to improve upon there.

All '96 and newer models sold in the U.S. Have the "On-board Diagnostics version 2, (OBD2). That includes an oxygen sensor ahead of the catalytic converter to tell the computer how to fine tune the air / fuel mixture, and it has an oxygen sensor after the converter to tell the computer how efficiently the converter is working. V-6 and V-8 engines can have a converter on each side and four O2 sensors. Older versions had both sides feeding into a single converter, then just one O2 sensor in the pipe going out. The few custom dual exhaust setups I've seen split the exhaust pipe after that last oxygen sensor. That's done for looks and sound. It won't gain much in performance or fuel mileage. The converter becomes the tight spot for air flow, and it's really not very restrictive.

You can't tie two oxygen sensors together. The sensor generates a small voltage corresponding to the oxygen in the exhaust gas compared to the oxygen in the outside air. That voltage ranges from 0.2 to 0.8 volts. The goal is to tell the computer if the unburned fuel and air is too rich or too lean. Ideally, if the mixture is always perfect, you might expect to see a steady 0.5 volts but that will trigger a fault code because the system doesn't work that way. In a properly-running engine you will see that voltage bouncing from real low to real high a couple of times per second. When the exhaust goes lean, the unburned oxygen is stored in the catalyst until it is needed. When the system goes rich a fraction of a second later, the unburned fuel mixes with the stored oxygen and is burned. The converters today are so efficient that you can suck on the tail pipe with the engine running, and live to tell about it! WHEN that converter is working properly, the gas coming out of it will be a little lean for a relatively long time, as in a minute or more, then a little lean for a long time. While the "switching rate" for an upstream sensor is a couple of times per second, the switching rate for a downstream sensor might be a couple of times per minute.

When the converter loses its efficiency, no change takes place in the composition of the exhaust gas between the time it enters and leaves the converter. Since both O2 sensors are seeing the same thing, they switch between rich and lean at the same rate. That doesn't happen all of a sudden. Instead, as the converter's efficiency gradually decreases, the downstream sensor's switching rate gradually increases. There is a threshold programmed into the computer at which point it knows the converter isn't doing its thing, and it sets a fault code for "catalytic converter efficiency" and turns on the Check Engine light. You can actually watch that on a scanner. The front sensor will be bouncing back and forth and the rear one will be steady.

If you imagine the O2 sensors as tiny batteries, they each develop a small voltage. If you connect a good car battery in parallel with a dead one, current will flow between them until the voltage equalizes and remains steady. That's not the goal though with the sensors. They are supposed to be varying in voltage. I don't know if current can be pushed into the sensor with the lower voltage, as with the car batteries, or if the computer would just see the higher of the two voltages. At any rate, the voltage seen by the computer won't be switching between rich and lean at the proper rate. When one goes lean, the other one might be going rich, and vice versa, so the computer will set a code for "system running too rich too long" and it will try to correct that by reducing the amount of fuel it commands from the injectors. That applies to the front sensors.

For two rear sensors tied together, as you're proposing, I don't know what would happen if one was switching very slowly, like normal, and one was switching rapidly. There are a number of self-tests the Engine Computer is designed to perform at certain times. Usually you don't know when that's taking place, but the computer might command an unusually lean or rich mixture long enough for the results to show up at the second sensor, then it can watch how that sensor responds. It may do that to each side of the engine at different times to insure you don't feel it taking place on the highway. Chrysler calls that series of tests a "global good trip". If that passes at some point in the recent past, the computer is happy and the vehicle will pass emissions testing on some states.