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*ElectronicsTech
*ElectronicsTech, Customer Service
Category: Electronics
Satisfied Customers: 9839
Experience:  I have over 15 years experience as an electronics repair and troubleshooting technician.
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My 2007 chrysler grand voyager went into limp mode with the

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My 2007 chrysler grand voyager went into limp mode with the abs light, engine management and 2 other lights coming on. I drove for a further 4 miles before switching off, it would not restart. The breakdown technician diagnosed an alternator fault, and the car was recovered to a local garage, a new alternator fitted [plus drive belt] the battery charged, fault codes cleared, and I had the car back. That was 2 weeks ago.
Since then the engine managemt light has intermittently come on when starting, sometimes when on it has been in limp mode, and other times not.
I have returned to the garage 3 times they have cleared the fault [P0700], each time it comes back. Then, last weekend i realised that i could get it to drive normal by stopping, switching off and back on again; sometimes it worked on the 1st restart, another time 6 or 7 restarts were needed - the light stayed on but as long as it drove normal - until today !! [and for the last 3 days it had behaved perfectly on about 15 separate occasions]
Today I cannot get it out of limp mode [30 stop/starts], light on. That 1st garage couldnt see me today, but another did, and they could not clear the fault, same code,and saying its the TC system [ECM/PCM/TCM].
My local chrysler dealer cannot look at it till next thursday, what is your opinion ? Can i bypass anything etc etc?
Thanks
Submitted: 2 years ago.
Category: Electronics
Expert:  *ElectronicsTech replied 2 years ago.
Hi,
My name is***** will assist you.
I am sorry to hear that you are having this issue.
Yes. That sounds like the correct diagnosis. The P0700 is the Transmission Control Module. This sounds like the TCM was affected by the alternator failure. The TCM requires 12 volts to function properly, when three voltage dropped below that it must have caused the TCM problem. The TCM had an internal memory that learns how you drive, if that memory was corrupted then it will have to be reprogrammed or flashed by the dealer. Then it v will have to go through the relearn process. There is not anything that can be done other than that, however if you need to drive the vehicle until the dealer appointment you can disconnect r negative side battery cable for 5 minutes when it goes into limp mode. Then you will be able to drive normally for 3 to 5 key cycles.
Customer: replied 2 years ago.

Hi Randy, thanks for your help..a couple of further questions...

its OK to disconnect the negative battery terminal when engine is running? And how many times can i do this for?

the garage that fitted the new alternator said there was a blown fuse that had to be changed before the engine would start..is it likely the recovery driver caused the damage to the TCM when jumpstarting the car to load/unload from recovery truck?

is the TCM located inside the gearbox?

Expert:  *ElectronicsTech replied 2 years ago.
When you disconnect the negative battery the engine and ignition need to be in the off position.
On the damage to the fuse and controller, it was most likely damaged by the alternator. The alternator probably shorted when it failed and that is when the main fuse was blown. It is also the same thing that would have happened if you connect the jumper cables backwards, but the most likely cause would be the alternator.
The TCM is mounted near the front tire on the drivers side of the vehicle inside the fender well.
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Expert:  *ElectronicsTech replied 2 years ago.
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