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Code 41 Serial Comm

1947 Views 2 Replies 3 Participants Last post by  vetteoz
Greetings, new member here; I have been on the CF for a long time, but not much help over there.

I am working on a '92 6spd, bone stock except for aftermarket stereo. I'm hoping you electrical gurus can help me out. Here's what I know:

1. Car won't start - CCM code C41 Loss of serial communications
2. Module 4 (ECM) displays Err, so does Module 9 (EBCM)
3. C68 climate controle flashing LED - code 10, UART failure
4. A/C 5AMP fuse under hood (under the coolant tank) blown. Noticed it was blown after the no-start, replaced it, blown again; not sure when it originally blew.
5. Per the FSM on CCM code 41, have determined the serial data line (CKT 800) has a short to ground. I have disconnected ECM, EBCM, CCM, C68 and still have short to ground. Can even verify by jumping ALDL pin 'M' to ground.

Anyone know if the A/C fuse blowing is connected to this serial line short? I'm assuming it is. Where should I start looking for this short, any usual suspects to start with?

If not, I want to try disconnecting every component that ties into the serial data circuit to eliminate suspects. I plan to remove the following:
- A/C programmer
- I/P (speedo/gauges)
- All the whiskey from my bottle to ease this pain :food-smiley-019:
1 - 1 of 3 Posts
sounds like you have a short or a vats problem.
DTC 41 is the CCM not talking to the ECM ; unrelated to VATS
1 - 1 of 3 Posts
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