My 04 Town & Country's reverse lights no longer function. The dealer said it is a defect in the body computer. This is very expensive!
The question raised concerns the use of a used body computer. Dealer says that once it is programmed it can't be reprogrammed by the dealer. Does the dealer have this right, do I need a new computer?
We have no idea if your dealer got it right without a lot more information. What troubleshooting was performed and what results on that troubleshooting led to the diagnosis received?
No reverse lights can be caused by many problems. For example: a fuse may be blown, you may have a bad common ground, both bulbs could be out, the reverse selector switch/contacts may be defective, wiring to the reverse lights or to the switch could be defective, etc. . I'd want to know they ruled out everything else and that the signal from the gear selector switch that goes into the computer was correct and that the output from that computer that drives that circuit was not.
Good luck
Bob
The dealer told me they were able to activate the rear lights which their computer system. That answers at least some of your questions.
Assuming the computer is defective, are they correct that I can't merely pop in a used one but must purchase a new one for them to program?
If only the reverse lights are an issue and your reverse lamps are only for reverse, I'd attempt using a simple relay off the reverse signal.
No it does not. Did the scantool also at the same time show the switch input from the gear selector switch to be working?
The explanation your being given makes no sense given how computers are designed. Your computer uses a power circuit that drives the reverse lights and carries a lot of power. If there is going to be a problem in the computer it is most likely to be here, where the higher power components are most likely to fail. In that case nothing they did with the scantool would make the rear lights come on.
By contrast the gear switch input to the computer is either open or closed. If the sensor wire were to be crushed and shorted out, it would be the same thing as closing the switch contacts - it would not harm the computer. If the sensor wire was to be crossed to a hot lead in the car it would be the same thing as a logic high - electrically the same thing as an open contact to the computer.
I thought in any case with that vintage that the transmission computer used a fully electronic gear selector. If the gear selector switch was broken then how would the vehicle even go into reverse at all?
You need to bring it to a shop that specializes in automotive electronics first. I am not sure how the trans computer communicates with the body computer I had thought it was by the shared bus. The diagnostician needs to jack into that bus and see if the trans computer is showing a reverse indication AND more importantly, that for that year that the body computer is even using that indication, and does not have a separate input to a reverse switch somewhere, such as inside the transmission.
If you find one in a T&C with exactly the same options and programming as yours, there should be no reason you can't use it. That includes exactly the same anti-theft programming of course. But, if it was my vehicle and it really was the computer I would not touch the computer. How often do you use reverse? Very seldom. How often are reverse lights even seen? Far less seldom than that. If it were me I would go buy one of those truck backup alarms, and wire it and the reverse lights to a toggle switch near the steering wheel. In the few situations where your backing into traffic where the traffic can actually see your reverse lights, then use the toggle switch. You can drive, can you not? If so, then remembering to flip a toggle during a backup manuever should be well within your abilities as a driver.
Ted
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