Engine turns over but wont start

Tiny
CRAIG JASTER
  • 2001 DODGE INTREPID
  • 200,000 MILES

I got in my wife's intrepid to go to the store and it just cranks and cranks. There is no power to the inj/coil fuse, or the 02ssr fuse in the power distribution box under the hood. I had the odb2 run on it the two codes that came up were p0700, and p1698. I'm not sure where to go from here, I dont know where to start tracking down wiring or anything. Do I need to look at replacing the tcm and pcm. The car is over 11 years old and has a lot of miles on it, I'm not sure if it is worth the money or not. Any advice is going to be verry helpfull.

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Tuesday, November 22nd, 2011 AT 8:26 PM

19 Replies

Tiny
ASEMASTER6371
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The tcm and pcm are the very last things you look at. First of all, you need to get power to the fuse box for the accessories. I would check all the fusible links by the battery for one that is open. If there is, you need to find out why it burned up as it does not blow without a good reason. It may be wiring, or a failed component.

If you are not sure, let a shop do this for you that is expierenced at these types of repairs. It will cost you but is better than throwing parts at it that do not repair anything.

Roy

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Tuesday, November 22nd, 2011 AT 8:32 PM
Tiny
CRAIG JASTER
  • MEMBER

I swapped the relays around and nothing changed I will go through the fusible links to see what I can find open and go from there
Thanks

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Tuesday, November 22nd, 2011 AT 8:40 PM
Tiny
CRAIG JASTER
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Any chance you might be able to tell me where to find any more than the one between the battery and the altenator

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Tuesday, November 22nd, 2011 AT 9:22 PM
Tiny
CRAIG JASTER
  • MEMBER

The fuse panel does have power, its just those 2 fuses that dont have any voltage thats why I am having so much trouble figuring it out.

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Tuesday, November 22nd, 2011 AT 9:44 PM
Tiny
ASEMASTER6371
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There should be a group of them. Look around the fuse box. There may be 6 or 7 of them together.

Roy

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Tuesday, November 22nd, 2011 AT 9:49 PM
Tiny
CARADIODOC
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You have to check for voltage while cranking the engine. Voltage will appear at the coil, injectors, alternator field, and oxygen sensor heaters for only one second after turning the ignition switch to "run", then the voltage will go to 0 volts. You might hear the hum of the fuel pump for that one second. The voltage will come back during engine rotation, (cranking or running). It comes through the automatic shutdown (ASD) relay. The Engine Computer, (PCM), turns the ASD relay on when it receives pulses from the camshaft position sensor and the crankshaft position sensor. Somewhere around the early to mid 2000s they changed the strategy so the engine could still run when one of those sensors failed but before that signals were needed from both sensors for the ASD relay to turn on.

To test the entire ASD switched circuit, connect a test light to the positive ignition coil wire, the 12 volt feed wire to any injector, or either small wire on the back of the alternator. The 12 volt feed wire is often dark green / orange. Whatever the color, it will be the same on all injectors and the coil. Watch for the test light to light up for one second when you turn on the ignition switch. A digital voltmeter might not respond fast enough for you to see it. If you see that one-second pulse, the ASD relay and wiring are okay and the computer has control of it. No need to check fuses.

What's important is if that voltage comes back during cranking. In the rare event it does, you have to determine if you're missing spark or fuel pressure. Usually it will be the fuel pump that fails to start up. Banging on the bottom of the tank often gets them going. Unlike GM fuel pumps that suddenly leave you sitting on the side of the highway, Chrysler pumps almost never quit while they're running. They typically intermittently fail to start up after being turned off.

There have been times no diagnostic fault code is set related to the cam and crank sensors. In that case it is helpful to have the Chrysler DRB3 scanner connected or an aftermarket scanner that can display live sensor data and has a "no-start" troubleshooting menu. It will display those two sensors with "no" or "present" to indicate if signals are being received from the sensors. Even if it does finally set a code related to a sensor, that never means "replace the sensor". While it's true the sensor is usually the cause of the problem, the code really means that's the circuit that needs further diagnosis. There could be a wiring problem such as a corroded connector pin or cut wire.

One of the strategies the Engine Computer uses to know when to set a fault code is if it's getting a signal from one sensor, it had better be getting a signal from the other one. They have their ground return wire and 5 volt, 8 volt, or 10 volt feed wire in common. If either of those wires are open circuit, (cut, or corroded at the splice), neither sensor will produce a signal. The computer will not know the engine is rotating so it won't set a fault code related to the two missing signals.

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Tuesday, November 22nd, 2011 AT 10:11 PM
Tiny
CRAIG JASTER
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No luck on any other fusible links. The codes are saying that there is no bus communication between the pcm and tcm and the tcm has a fault code also. So if there is a broke wire in between the two I guess that might explain the codes. I do have voltage to the asd relay which is what supplies power to those two fuses. Acording to the haynes manual, the pci supplies ground to them, and the both have ground. Do I need to be looking for a break between the asd relay and the 02ssr fuse then? This is a huge mess here.

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Tuesday, November 22nd, 2011 AT 10:19 PM
Tiny
CRAIG JASTER
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That should be helpful, I know the fuel pump is going, I can start the engine if I jump a positive to the inj/coil fuse in the power distribution box, then the car runs and drives fine, but the alternator doesnt charge the battery, and the indicator lights and gauges on the dash go crazy.

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Tuesday, November 22nd, 2011 AT 10:28 PM
Tiny
CARADIODOC
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I think you've unknowingly identified the problem. Measure the voltages on all three wires on the back of the alternator while the engine is running. You'll find full battery voltage on the large output wire bolted to the back. One small wire must also have full battery voltage. The other one will have less but not 0 volts. 4 - 11 volts is typical. I suspect you're going to find 0 volts on both small wires. Since you're jumping battery voltage to the coil / injectors and the engine runs, the alternator is on that same circuit, ... It should be working too. If you find 0 volts on the small wires, there has to be a break at the splice for all the wires in that circuit.

If you do find battery voltage on one small alternator wire, and the same voltage on the other one, that would suggest the Engine Computer isn't turning on the voltage regulator built into it, and that's why the alternator isn't recharging the battery. That would point to some other cause.

Of course there could be two totally separate problems but that isn't real common. It IS common for the brushes to wear in the alternator and cause intermittent charging. Those brushes can be replaced easily, often without even removing the alternator from the engine. That problem should be addressed last though because it won't be related to the no-start problem.

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Tuesday, November 22nd, 2011 AT 10:44 PM
Tiny
CRAIG JASTER
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Ok so I took the alternater off and had it tested and it was bad, so I buy a new one ($100 that I dont have) and now it still wont start any other ideas out there?

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Thursday, November 24th, 2011 AT 3:02 AM
Tiny
CARADIODOC
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I just replaced the brush assembly on my alternator. Nine bucks for the part and an hour to remove it from the engine and replace the part. If you would have let us know I could have told you how to test it with an ohm meter and replace the brushes if that was the problem. "Darn the bad luck".

For the no-start, check the voltage to the ignition coil or injectors. See if you have 12 volts there for one second after turning on the ignition switch, then again during cranking.

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Thursday, November 24th, 2011 AT 6:46 AM
Tiny
CRAIG JASTER
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I cant get any voltage to the fuse labeled lnj/02ssr, but if I jump power to that fuse, it starts and runs fine

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Thursday, November 24th, 2011 AT 1:24 PM
Tiny
CRAIG JASTER
  • MEMBER

Any chance these symptoms may be bad camshaft or crankshaft positioning sensors? If so, how would I test these? If nothing I could replace them and cross my fingers on it. They're about $20 each. I'm pulling my hair out here. All these computers and wiring aint nothing but a headache. You wouldn't have this problem with a carburetor.

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Thursday, November 24th, 2011 AT 3:59 PM
Tiny
CARADIODOC
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Boy I hear you about all the unnecessary, unreliable computers. I just got done typing another novel related to my disgust with the car designers, but I do have to admit, the Engine Computer in my daily driver '88 Grand Caravan has been extremely reliable and the tail pipe is real clean compared to my carbureted cars.

First of all, which engine do you have? I only have '00 and '02 service manuals but the circuitry should be the same. Naturally they don't label the fuses the same way in the manuals as they do on your fuse box cover. I drew up a diagram of the fuse box layout. Tell me which fuse, by the letter, that is missing the voltage, then I should be able to find it in the manual and see where it comes from.

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Friday, November 25th, 2011 AT 2:28 AM
Tiny
CRAIG JASTER
  • MEMBER

Ok, the engine is a 2.7, the fuses that are not getting voltage are S and T from your drawing. They are both supposed to be directly fed off of the auto shutdown relay. The auto shutdown relay does have power good constant voltage, and keyswitch voltage, and the relay itself tested good, but the voltage is not getting to the 02ssr or inj/coil fuses. I thaught maybe buying the haynes manual for the car might help me out, but basically it's telling me to look for the things that i've already looked for. I'm not by any means an expert mechanic, but i've been working on my own cars for the past 15 years and never ran into something that I couldnt figure out before, and this one has got me hailed.

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Friday, November 25th, 2011 AT 4:04 AM
Tiny
CARADIODOC
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Double-check that missing voltage for the first second after turning on the ignition switch. I added the letters to the ASD relay in my drawing. Sounds like you found battery voltage on "A" and "B" all the time. That is normal. Terminal "D" should have voltage for one second after turning on the ignition switch, then go back to 0 volts. Measure that with the relay in place. If it's hard to access the relay terminal, fuses "S" and "T" will have it or you can back-probe any dark green / light green wire at any injector or ignition coil. If that voltage doesn't appear for one second, there is something wrong with the Engine Computer or there's a break in the dark blue / yellow wire going to pin 3 in connector C3 on the computer. If you back-probe terminal "C" of the ASD relay while it's installed, you will find battery voltage there. Grounding that terminal will make the relay click on.

If you do find voltage on fuses "S" and "T" for one second, that proves all of that circuitry and relay are okay and the computer has control of it. If the voltage doesn't come back during cranking, suspect the camshaft position sensor and crankshaft position sensor. On older cars both of them had to be working for the computer to turn on the ASD relay. On newer models the engine will run when one fails. Your engine might run on just one sensor when you jump 12 volts to fuses "S" and "T", but the computer might not be turning the ASD relay on to supply that voltage due to a missing sensor signal.

Without hooking up my tv test equipment, and in the absence of a diagnostic fault code, there's no easy way to tell if one of those signals is missing except with the scanner. It will display "no" or "present" for each one during cranking or running.

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Friday, November 25th, 2011 AT 5:09 AM
Tiny
CRAIG JASTER
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Ok, I have replaced the crankshaft positioning sensor, and it changed nothing. But I was able to get it running, again with a jumper wire. I grounded terminal C with the ASD relay in place, and the engine started fine. If I'm correct, the computer controls ground rather than power, so the lack of a ground could mean that there is a missing sensor signal correct? I'm going to try for the camshaft positioning sensor and see what happens there. Do I need to have the computer reset after replacing the sensors?
Thank you verry much for helping me out with this.

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Saturday, November 26th, 2011 AT 12:28 AM
Tiny
CRAIG JASTER
  • MEMBER

THANK YOU again for all your help. I've spent all week pulling my hair out looking for the answer to my question, and finally found it tonight. The Camshaft Positioning Sensor is all it was. Thank God it wasn't the computer. The engine light is still on, but I'll get that taken care of tomorrow. Once again THANKS:)

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Saturday, November 26th, 2011 AT 4:48 AM
Tiny
CARADIODOC
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ALL RIGHT! One in a row! Gonna make some notes to myself that two sensors are needed to turn on the ASD relay but it can run on just the crank sensor. For my reference, do you recall if you had 12 volts coming from the ASD relay for that first one second? I think you would.

The alternator problem was totally unrelated. Very uncommon to have two problems at the same time. Darn the bad luck, but happy you can buzz off, ... Ahh, ... I mean SAIL off into the sunset.

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Saturday, November 26th, 2011 AT 6:02 AM

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