1998 Seville STS ECM-Modules Issues

[makavelli1]

Please Help, Reverse lights only work & Fuel Gauge goes to Zero 1.5-2 minutes after battery reconnected, I have an engine misfire (P300) many faults too many list almost like the brain that communicates with all the module is bad, any help much appreciated before I send this ride to the Junk Yard (1998 very low miles its a shame)
thx

[basscatt]

Please Help, Reverse lights only work & Fuel Gauge goes to Zero 1.5-2 minutes after battery reconnected, I have an engine misfire (P300) many faults too many list almost like the brain that communicates with all the module is bad, any help much appreciated before I send this ride to the Junk Yard (1998 very low miles its a shame)
thx

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OK - so everything went haywire after the battery was reconnected - why was battery disconnected?

Is the battery good? Has it been tested? Load test done?

What is the voltage displayed in the DIC key - engine off?

What is the voltage displayed in the DIC with the engine running?

Could be a PCM brain fart - clear all the codes and see what comes back.

[makavelli1]

Hello,
I disconnected the battery because a previous thread said it would reset the modules and his system all worked, I went to the boneyard and replaced the Rear Interface Module and still have the same problem, it all works when the battery is reconnected for 1.5mins..then all goes haywire, wondering if the main computer is conducting a self check and it takes about 1.5 minutes to fault out. Thanks for replying

[maeng9981]

Is your battery healthy? You skipped the most important test Basscatt told you to do.

[makavelli1]

Okay let me start over, I bought this vehicle with fuel guage, reverse light inop. After a couple of weeks I would try and start the car and the battery was dead, I bought a new battery and still the car would have a dead battery after a day or so, troubleshot and pulled fuses until I found that the problem was a draw on the CVRSS line, I left the fuse out and the battery holds now. I then replaced the Rear Interface Module that I got from the junk yard and still I have no fuel guage and reverse lights after reconnecting the battery ( I disconnected the battery just trying to see if it would reset the modules) because I have so many different module faults it leads me to think that all these modules talk to a main computer that might be causing all others to fault out/conflicts. BTW: I still have not repaired the CVRSS issue but want to work on one at a time. Any help is appreciated and willing to try many thanks

[MoistCabbage]

What codes are you getting? LIST THEIR DEFINITIONS as well.

[maeng9981]

A low battery, or disconnecting the battery will bring a lot of false codes.