Blown427conv

I just finished installing a rebuilt LS1 in my 2000 C5 that went into shallow flooded street water and hydrolocked. The BCM got wet and when I took the cover off I found it has 2 burned Siemens creamic relays on the circuit board. My power windows, interior lights, hatch release, and cranking do not work, but everything else seems to work including power seats, HUD, gauges, etc. I cranked the engine over by crossing the starter lugs and it fires right up, but dies immediately. I was under the assumtion from previous threads that the PCM ran the engine. Would the fried BCM keep the engine from running?

Blown427conv

One other question, can the BCM be programmed without the car present if the VIN is known?

ersatz928

The BCM must work properly for the engine to run (because the anti-theft function is performed by the BCM). You must get the correct replacement part-number BCM for your model-year, there are 2 or 3 different part-numbers used in the C5. It will have to be programmed by the dealer, using a Tech-2, to set the option codes and match the resistor-pellet value for the anti-theft system. Then the security password between the BCM and PCM has to be learned.

Bill Curlee

There is an emergency BCM/PCM handshake procedure that you can use at home but it will not set any up any of the RPO codes that were in the old BCM. The TECH II has that capability. The procedure will allow the BCM to function with the PCM and the car will run.

I dont have the procedure at work.

BC

Allthrottleandsomebottle

My 97' had the BCM going bad............It would go into 4 cyl limp mode and a few other anoying things .
I could fix it by deleting the codes via the DIC. Once I turned off the car for a food/fuel stop, unbolt one lead on the battery for 30 seconds, reconnect and it would start. A new BCM did the trick as you can not reprogram a 97' BCM!

Blown427conv

Guess I'm going to have to have the car towed to the theiving dealership after I get a new BCM for it. Ugh...

Blown427conv

I am going to try to replace the 2 burnt relays on the BCM if I can find them for sale somewhere. Maybe I'll get lucky and it will run again.

Blown427conv

Does anyone know what this handshake procedure is(below) so I can drive the car over to the dealership with a salvage yard BCM in lieu of the wrecker hauling it?
"There is an emergency BCM/PCM handshake procedure that you can use at home but it will not set any up any of the RPO codes that were in the old BCM. The TECH II has that capability. The procedure will allow the BCM to function with the PCM and the car will run."

timemender

Disable the headlights, daytime running lights; turn off the radio, etc., in short cut the power to all lights and accessories. This is to prevent battery power drain. Battery should be FULLY CHARGED before this procedure begins.

Turn the key to the "on" position, until the 'security' light goes out or quits alternately flashing between "Security" and "Battery". This relearn period always takes 10 minutes. How long does this take? 10 minutes. How long do I have to wait? 10 minutes.

After security light is no longer displayed, turn the key to the off position!

Wait 5-10 seconds and repeat the above procedure. two more times for a total of 3 start/relearn/attempts, remembering to shut the key off between each 10-minute relearn procedure.

This will take 30 minutes; no less.

If the car fails to start you did one relearn step (or all of them incorrectly).

If you left your headlamps on until the battery went dead and voltage dropped below 10.5 volts, no amount of relearn attempts will be learned!

P.S. Waiting a full 11-minutes instead of the “10-minutes” in the above procedure will insure better results – in other words you MUST allow at least 10-minutes to pass in each above procedure. (Waiting at least 10-minutes in required, but no sense in waiting 15-minutes for example)



EDIT - Options will have to be reprogramed into the replacement BCM with a "TECH 2".

Car will run and drive OK after the THREE 10-minute cycles are properly executed.



- Jim

Blown427conv

Great, thanks for the info. I'm assuming the car will run and drive ok after this, but all the options may not be functional?

timemender

Options will have to be reprogramed into the replacement BCM with a "TECH 2".

Car will run and drive OK after the THREE 10-minute cycles are properly executed.

Bill Curlee

Hereis what I have::


BCM/PCM RELEARN PROCEDURE


You will need to conduct the PCM/BCM relearn process. This matches their handshake ID's and allows them to talk to each other.

Do this before you worry about VATS issues:

1. Turn on the key for 11 minutes.
2 Turn off the key for 30 seconds.
3. Repeat 1&2 two more times.
4. Turn on the key for 30 seconds.

The car should start and run with the new BCM. Good luck and report back on your progress.
Shirl
SD Racing Enterprises
Aguila, AZ
Coutersy of MrEracer


This will sync the PCM to the New BCM but all of your RPO options will not be retained. You will need a TECH II to program them into the new BCM.

Bill Curlee

timemender

I thought thats what I said in my post. Re-reading it I see a lot of rambling that you cleared up.

However you laid out the proceedure in easy to read format. I should have left out all the stuff about the security light.

Thanks for jumping in to make the directions clear.



Bill - Does the key have to be "OFF" for 30-seconds as opposed to 10-seconds? Or is 30-seconds stated to insure that at least 10-seconds have passed?


-

Blown427conv

OK, I have a salvage yard BCM on the way with the same service number. Hopefully it will be running soon so I can drive it to the dealership vs towing it. Thanks for the helpful information. Maybe I'll get lucky and the donor car had all of the same options mine has so I won't have to re-program it aside from the handshake method.