Codes P0700 and P0480, stuck in limp mode and can only be driven 35 to 45 mph

Tiny
DAVISETHAN
  • MEMBER
  • 2004 CHRYSLER SEBRING
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
The car went into limp mode and I cannot figure out the issue with it. It is only throwing two codes P0700 and P0480. I changed the shift solenoid pack and the transmission fluid was changed with a new filter before I got the car. The car started shifting a couple weeks after I changed the solenoid pack it worked great for a few days then the alternator went bad. So we left the car sitting for a couple of months. Then put a new alternator and battery in the car but it is no longer shifting again.
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Saturday, July 25th, 2020 AT 12:58 PM

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Tiny
CARADIODOC
  • EXPERT
P0480 - Cooling Fan 1 Control Circuit Malfunction

P0700 - Transmission Control System Malfunction

I suspect you're reading these fault codes with a code reader or by using the car's Check Engine light. Most simple code readers only read fault codes in the Engine Computer. Code 700 just means there are other fault codes in the Transmission Computer that need to be read. You have to use a scanner to access the Transmission Computer to read the codes in it. Those codes will give us an idea of where to start the diagnosis.
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Saturday, July 25th, 2020 AT 1:10 PM
Tiny
DAVISETHAN
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Where can I go to buy/use a scanner and get the rest of the codes out? I have a code reader. Thank you for the response.
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Saturday, July 25th, 2020 AT 1:15 PM
Tiny
CARADIODOC
  • EXPERT
You don't want to buy a full scanner unless you can get a lot of use out of it. I have a Chrysler DRB3 for all of my older vehicles, but that one had a list price of $6,200.00. For my newer Ram, I bought a Snapon Solus Edge from eBay for $1,800.00. The biggest disadvantage to Snapon scanners is they charge an unreasonable price for annual updates, and you can't skip any years. Mine is updated through 2017. If I want to have it updated to 2020 models, I have to buy the 2018 and 2019 updates first, at around $1000.00 each.

The DRB3 first became obsolete on 2004 Dakotas and Durangos, and finally on the 2008 Jeep models. It will work on your car, and other Chrysler models back to 1998. With an extra plug-in "Supercard", it will work on Chrysler models back to 1994 models, and it will do emissions stuff on all car brands sold in the US. Starting with 1996 models. For that reason, a lot of independent shops bought them. Since they are obsolete now, you can find them on eBay, and you may have a local shop with one they'd like to sell so they can invest in something newer. The last time I searched on eBay, the DRB3s were going for around $2000.00. I have multiples of all the extra plug-in cards that I sell at the nation's second-largest old car show swap meet. The original plug-in card lets the DRB3 work on 1983 through 1993 Chrysler models. (For anyone wanting a dealer-level scanner for use on only '95 and older Chrysler models, look for the older DRB2). You can find these for less than $200.00, but you have to use them with the correct cartridge. The last one made was for a '94 model, (yellow sticker to match the service manual covers), and it was an all-in-one cartridge that covered all Chrysler models from 1983 through 1995.

For what you need to do, I would suggest checking eBay for an out-of-date Snapon Solus Edge. When a shop lets them get out-of-date by four years, they can spend $4,000.00 to bring it up-to-date, or they can just buy a brand new one for just a few hundred dollars more. For this reason, the out-of-date models lose their value very quickly. That is good news for you. Some of these updated through around 2012 to 2014 can be found for around $700.00 to $800.00.

All three of these I described will access all the computers on your car. That includes the Body Computer, Anti-lock Brake Computer, Air Bag Computer, radio, instrument cluster, and a bunch of others I can't even think of right now. Scanners are "bi-directional", meaning they communicate both ways. They read and display data from the various computers, and you can talk back to them and command them to perform various functions. For example, you can command the Engine Computer to cycle the radiator fan relay on and off once per second so you can perform live diagnostic tests in that circuit.

For your transmission, among many other things, the DRB3 will read the "clutch volume index, (CVI)". That's a set of four numbers corresponding to the volume, in ccs, of fluid it takes to apply each of the clutch packs. An experienced transmission specialist can tell by those numbers the amount of life left in each clutch pack. The Transmission Computer learns those values as you drive, and constantly updates the software's shift schedules to maintain a smooth, clean shift like when it was new. The disadvantage is you don't get the two or three years of gradual sloppy shifts that tell us a rebuild is in your future. One day the transmission shifts like new, and the next day it can't update enough to overcome the excessive wear, then the slipping between shifts gets detected, a fault code is set, and the computer goes into limp mode. Limp mode is only to allow you to drive very slowly to a repair shop without needing a tow truck. Don't try to drive it that way very far. Limp mode keeps the transmission in second gear.

As an alternative to a scanner, the people at most auto parts stores will read fault codes for you for free. They used to use the simple code readers that only worked on Engine Computers, but now many of them are using scanners or more advanced code readers that can talk to some of the other computers. If you can find one that uses a scanner that can access your Transmission Computer, it will display the fault codes.

Be aware that fault codes never say to replace a part or that one is defective. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a sensor or other part is referenced in a fault code, it is actually the cause of that code about half of the time. Before we waste your money on an unneeded part, we have to rule out wiring and connector terminal problems, and mechanical problems associated with that part.

One last comment related to scanners. You might want to look at Harbor Freight Tools if you want to invest in a scanner. They have a model for around $1100.00, as I recall, that looks very much like the Snapon Solus Edge. I don't know anything about it or how it's updated, or its quality, but for the features and price, it might be worth looking at.
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Saturday, July 25th, 2020 AT 3:05 PM
Tiny
DAVISETHAN
  • MEMBER
Thank you for the information and your time. I'll see if I can find a shop that can pull the codes for me. I do some work on cars but I doubt I would get a lot of use out of a scanner. How many connectors are on the transmission I can clean the connectors and see if I can find any bad spots on the wires. When I put the solenoid pack on it had a plug or two on it are there anymore around the transmission that l should check? I thought it was a possible wiring issue but I didn't know where to start with it. Could a broken wire cause it to engage limp mode? I appreciate your help. It used to be a fun little car to drive.
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Saturday, July 25th, 2020 AT 8:00 PM
Tiny
CARADIODOC
  • EXPERT
We don't like to do things that might make the problem stop acting up because then you never know if you really fixed it. You could wiggle a connector with a corroded terminal while pulling the plastic wrap off the harness, then the terminals might make a good connection and the system will work, only to fail again in the middle of rush hour traffic or on a lonely country road on a Saturday night when all the shops are closed.

Because so many electrical problems are intermittent in nature, I try to be very gentle to not disturb anything that might start the system working again. I want it to stay in the defective state so there is a defect to be found.

The fault codes are always the place to start. Fortunately even if the defect goes away, the fault codes stay in memory for at least the next 50 engine starts. They might self-erase after that, and they will be erased if the battery or computer is disconnected. Be sure to have the codes read before doing anything that will lose memory power to the computers, otherwise that valuable information will be lost.

The transmission can be put into limp mode if the computer detects an electrical problem, typically a break in a wire or between a mating pair of connector terminals. It can detect incorrect switch position data from the transmission range sensor, formerly known as the neutral safety switch, and it monitors pressures in some of the hydraulic circuits. One of the more common defects is when some of the clutch plates are worn beyond their limits. I started to describe this briefly, previously. In all of the older hydraulically-controlled automatic transmissions, that plate wear caused "engine runaway" between up-shifts. That's when engine speed would increase until the next higher gear finally locked up.

Among the long list of "firsts" that Chrysler developed that benefited car owners, they were the first to have a computer-controlled transmission in 1989 models. Part of the software design monitors the volume of fluid it takes to fully apply each of the four clutch packs. When the clutch plates wear thinner, it takes more fluid volume to fill in behind them. To overcome that engine runaway, those volumes are constantly being updated in the computer's memory. As that wear progresses, the computer begins to apply third gear, for example, just a little sooner, before it releases second gear. That gives the next clutch pack extra time to fully lock up, thereby eliminating that slippage between gears. The problem with this is you don't get the two or three years of warning a rebuild is going to be needed soon. That slippage is hidden until the day comes when no amount of additional fluid will lock that clutch pack up.

The Transmission Computer monitors input shaft speed, (engine speed via the crankshaft position sensor), and output shaft speed from the speed sensor in the transmission. Based on the gear ratios that are programmed in at the factory, the computer knows how fast the output shaft must be turning for the given input shaft speed it sees. When those two don't agree, it's because of that slippage in one of the clutch packs. That will send it into limp mode, and the fault code will be related to "incorrect gear ratio". That can also be caused by a defective speed sensor, although it is more likely to be detected as such, and the fault code will be more specific.

When you disconnect the battery, it can take up to two miles or about a dozen shift cycles for the computer to relearn the clutch volume data. Until then, the transmission might shift like a race car. It used to be common after performing any service that required disconnecting the battery, to take the car on a short test-drive to perform the relearn, for customer satisfaction, or at least to make the car owner aware of the need to wait for that to take place. It is now possible with the DRB3, and probably some of the better aftermarket scanners, to do that relearn while sitting in the shop. Most mechanics don't bother to do that because they need to add an extra charge to the bill for using the scanner, to help pay for that expensive equipment and the updates, and the car will take care of that on its own within a few miles.
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Saturday, July 25th, 2020 AT 11:12 PM

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