SRS Control Unit Replacement?

[dr_gn]

All, my wife has a 2001 Civic. The SRS light is on, and according to the local garage, the code can’t be read because the control module is ‘dead’.

They suggested getting a used one off EBay (can’t find one), but further digging suggests that even if I got one, it wouldn’t work because it needs coding to the vehicle’s VIN.

Question is: does anyone have any bright ideas on how to proceed, or is the car effectively scrap because a) it’s currently dangerous to drive, and b) it wouldn’t pass its next MOT?

Thanks in advance!

[LordLoveLength]

By ‘dead’ they may just mean ‘unable to communicate with’ which could be just a poor / corroded connection on the plug / socket of the module. It could be a poor earth or blown fuse.
All easy enough to check.

It could just be that their diagnostic machine can’t talk to it and it’s working just fine and reporting a genuine fault.

Does it have seat airbags? Very often the repeated seat movement breaks the wires in the seat loom to the body.

[dr_gn]

LordLoveLength said:

By ‘dead’ they may just mean ‘unable to communicate with’ which could be just a poor / corroded connection on the plug / socket of the module. It could be a poor earth or blown fuse.
All easy enough to check.

It could just be that their diagnostic machine can’t talk to it and it’s working just fine and reporting a genuine fault.

Does it have seat airbags? Very often the repeated seat movement breaks the wires in the seat loom to the body.

Thanks. No, it doesn’t have seat airbags. I guess I could take it somewhere else for a second opinion, but it’s £40 a time for a diagnostic…

[Smint]

That problem crops up now and again on that model of Civic, daughter had the same problem.

You need a proper old school car sparky, the one we use found the problem and fixed it, told her it might re-appear at some point but it never did.

[Polly Grigora]

LordLoveLength said:

By ‘dead’ they may just mean ‘unable to communicate with’ which could be just a poor / corroded connection on the plug / socket of the module. It could be a poor earth or blown fuse.
All easy enough to check.

It could just be that their diagnostic machine can’t talk to it and it’s working just fine and reporting a genuine fault.

Does it have seat airbags? Very often the repeated seat movement breaks the wires in the seat loom to the body.

Am of the same opinion

Seat belt pre-tensioners come to mind, moving the seat can disturb plug/socket connections from main loom to seat

[dr_gn]

So to wrap up this thread (hopefully), As a last resort I took it to a local “old school” auto electrics garage, as recommended here.

Initially he was puzzled because it was an intermittent fault. Also, the code reader didn’t point to a specific fault.

By chance, on one of the diagnostics, he noticed alternator voltage was high - over 16v. He then tried it with all electrical equipment on in order to drop the voltage, and the issue was gone.

Turned out it was the alternator regulator. A new unit has solved the issue. Having since looked online for this problem, high system voltage can indeed trip the SRS light.

This also fits with the issue appearing immediately after jet-washing under the car - water probably got into the alternator and finished it off (after 21 years service).

Took him 2 weeks on-and-off to diagnose, but fair play to him; for now, the Civic lives on…Thanks all for the advice.