383LPE

after buttoning everything up after installing a clutch master and slave cylinder my 91 started acting up. the check engine light came on and the sys would flash. My manual led me to swap out the mem cals- (no change), SWAP OUT COMPUTERS (NO CHANGE), then I retrieved the CCM code 41. What would be the most likely cause of a loss of ECM serial data communications?

This am I am going to check the CCM connectors and anything else suggested.

Thanks in advance!

vinnies87

Code 41 - faulty or incorrect mem-cal : Check mem-cal lock tabs are secure.
Tes per helms:
1. ign off, clear codes; start engnine and run 1 minute or until code 41 sets
2. if code 41 sets: ign off; disconnect ecm connections ; probe terminals D3, D1, D10, A12 w/test lite connected to 12v
3. Light On: faulty connections or mem-cal or incorrect mem-cal installed
Light Off: Repair open ground CKT 450

383LPE

Thanks, but I am looking for help with the CCM code 41 "ECM serial data circuit - loss of data".

383LPE

ttt

art1217

On my 93, I solved the problem by replacing the ECM. Mine was temperature sensitive so I could confirm with an ice bag.

Problem also can be caused by open serial line. Shorted serial line has additional symptoms that you did not mention.

383LPE

ttt

also, how can I test for an open serial line?

Tom Piper

A serial line data loss can be caused by:
1) Serial line shorted to ground
2) Serial line open
3) No data being sent

Since there are supposedly two wires in parallel, it is unlikely that the line is open.

If your vehicle is like my '92, you can have four computers communicating on the serial line:
1) ECM
2) CCM
3) ASR/ABS computer
4) C68 Electronic climate control

Your car can run with only the ECM and CCM connected.
By disconnecting the ASR/ABS and C68 climate control connectors, you can eliminate them as being the problem -- if the problem still exists, this will leave only the ECM and CCM or the serial link itself as the problem. My problem was the ECM.

Tom Piper

383LPE

thanks tom, great responce. maybe you can help me trouble shoot this out.

This started after the clutch master install, and I am wondering if I disconected something with my big hands under the dash.

when I read the ccm code and got the 41 (ecm serial loss), the ccm gave me an ERR on module 4 and 7. I think these represent the abs and or the ac.

I secured another CCM and installed it, no change. I tested the circuits on the CCM plugs and things checked allright...I guess. I'll need to do some more, but this is very frustrating.

any tips on how to better check the abs or ac?

art1217

If you were rough behind the dash, there is Splice S222 that ties all the serial lines together that maybe damaged. On the 92/93 at least, it is located in the Intrument Panel Harness near the Cruise Control Module. also the service manual provides a diagnostic chart to follow for Code 41 that checks continuity, opens, and shorts.

383LPE

Thanks. That splice 222 is a nest!

I have worked through the diag chart, and am doing so again. I am trying to trace down a possible open to B+ on ct 800.

Ideas appreciated.

art1217

Hate to post the obvious. Did you check all the fuses?

383LPE

10-4, unless there are some I don't know about.

383LPE

ttt

C4.Taylor

I know this is an old post and I don't ecpect you to even reply but can you, or someone who knows how walk me through how to disconnect the "ASR/ABS and C68 climate control connectors"?