Hi All,

I have a 3800 series II swapped 87 GT with a stange issue and any idea will be much appreciated.

As the post title suggests I get a check engine light when I apply the brakes.. The CEL is like a 4'th brake light since it goes away quickly when releasing the brakes.

Has anyone encountered this?

Thanks,
Ronen

The first thing that comes to my mind is a wiring issue at C203 connector.

The CEL light and a lead from one of the brake switches both go to that connector.

The C203 is located under the center console, below where the OEM fire ECU lives.

C203-C is wired to the CEL light
C203-P is wired to the brake switch

I don't know if this is your problem, but it might be a place to start.

Thanks a bunch, super helpful!
I will check this out and update shortly.

quote Originally posted by olejoedad: The first thing that comes to my mind is a wiring issue at C203 connector. The CEL light and a lead from one of the brake switches both go to that connector. The C203 is located under the center console, below where the OEM fire ECU lives. C203-C is wired to the CEL light C203-P is wired to the brake switch I don't know if this is your problem, but it might be a place to start.

Dug deeper and all wires/connections at C203 look solid.. I did some checking around the brake pedal switch and it is not the brake switch triggering the SES light but the TCC switch next to it.

Additionally, I'm getting a P0341 code which I thought was a different issue all together but I have no idea anymore.

Any advice would be welcomed really.

Thanks,
Ronen

it's a wiring issue, follow oldjoedad's advice.

P0341 is camshaft position sensor code, irrelevant to your brake light, but possibly you have an unrelated issue.

[This message has been edited by jelly2m8 (edited 04-13-2024).]

The TCC switch on the brake pedal should be wired to C203-P.

If its wired to C203-C that is your problem.

C203-C should be wired to PCM C2-5 (clear). It is a brown/white wire.

[This message has been edited by olejoedad (edited 04-13-2024).]

Does it happen when your parked w/ transmission in neutral/park?
Or only when Driving?

If only when Driving...
Is likely Wiring problems that angry from iffy motor/trans mounts letting the engine pulling or pinching the wires.
Or bad exhaust melting the wires now then soon can cause a fire.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Thanks for responding!

It happens in all trans gears and when the car is both on or off..

[This message has been edited by Rightasrain (edited 04-23-2024).]

quote Originally posted by Rightasrain: Thanks for responding! It happens in all trans gears and when the car is both on or off..

Did you check the wiring at C203?