2000 FRC

Trying to figure out why my turn signals aren't working properly.
There are multiple other issues, but I don't care about those at the moment. I just need to get the turn signals working so I can drive the car.

The turn signals flash rapidly and sometimes normal.
When they flash at normal speed, the actual blinkers are working on all 4 corners.
When they blink rapidly, only the rear lights flash (really fast). The fronts don't flash at all.

Here's what's crazy. With the key in the ON position, engine not running and turn signal on, the BCM is switching back and forth.
You can hear it in this video clip.



Here's where I started.



Here's what it says as of this afternoon:



I have replaced the battery, both the Left and the Right DRL Relays, the hazard switch, the emergency brake switch. I have disassembled and cleaned the ignition cylinder, pulled both door harness connectors and checked for corrision (didn't check the actual female pins for slop), same thing for the ground termination blocks on the frame behind the headlights and on both A-pillars. I cleaned the ground under the battery as well.
Oh yeah - found that the BCM2 fuse was blown, but nothing changed after I replaced it.

Is it likely that I have a faulty BCM?



Other issues that I don't really care about, but may be related to help solve main problem:
Door Ajar message on DIC 95% of the time (replaced both door switches).
Door chimes 75% of the time after you remove the key. Computer thinks key is still in ignition.
Column lock was removed at the dealer years ago, but was not tuned out because previous owner was afraid he would lose custom tune.

 

Ttt

 

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Did it ever get WET? Sounds like it may have.

 

Not to my knowledge. I've checked all the drain tubes and none were clogged.

I've done that at least half a dozen times. The DRL issue is constant.

Diving back into it today. Will report back.
I sent a request for Bill C. to chime in, but haven't heard back. Hopefully all is well with him.

 

 

Okay. I've narrowed it down to the RH DRL. Code BO503 H C keeps popping up.
The blinkers work fine until you this disengage the emergency brake. At that point, the DRL's come on and trip the flasher and the blinkers go crazy. I have replaced the relay again with no luck. Going under the car now to check the wiring at the light itself.

 

Looking though the front bumper (air duct removed). Found a broken wire.
Not sure what it goes to, but I put it to ground and blinkers flash fast even without DRL's turned on (parking brake on).

 

Can't make heads or tails of this.
I've looked and looked, but I can't find CKT 1966 anywhere in the manual.

 

Its the light green wire going from the DLR R relay(38) to the BCM. Shows it in first pic of your last post.
What it looks like to me is the manual is basically saying check for a short going to relay 38, bad connections at relay 38 or relay 38 needs to be replaced. How this relates to your original problem I'm not sure.
You do need to figure out where that loose wire is supposed to be and reconnect it.

 

Right. I can see it in the diagram, but it doesn't help me a bit. I don't know how to read a wiring schematic. I'm sure there's a short in that circuit, but I have no idea how to find it.
I've replaced the relay and it didn't help.

Any ideas on how to find the short?

 

You have to test each wire in the circuit. Use your volt meter to check each wire to see if they have short to ground first. After that I would check each connector or splice. Did you figure out what the cut wire was?

The diagram identifies the wire by color and connector. You have to know what the abbreviations are though.

 

The broken wire was inside the same harness as the other wires that goes to that connector you see in the picture. There was an empty slot in the connector so I stuck it in there - no change.

I performed steps 2,3,5,6 and 8 from the service manual.
Probing the Batt terminals (step 2) did make the test light come on.
I don't have a Tech 2 scan tool so the only way I know to trigger the DRL relay (step 3) is to set parking brake with key off, turn on ignition and then release parking brake. When I did that, the test light came on. Shouldn't that eliminate a short to voltage in CKT 1966?

Next thing I did as a Hail Mary was to replace the Multi-Function switch on the column.
That didn't work either. (I have a car I'm parting out that I'm robbing parts from).

 

FYI - I just bought this car last week. the previous owner hit a dog a couple of years ago and cracked the front bumper cover so he replaced it. I'm guessing that's where the broken wire came from.

He had a quarter wedged in between the dash and the hazard switch that he would jiggle any time the blinkers started acting funny. We both figured that the hazard switch was bad so that's the first thing I replaced. It didn't work.

 

Did you actually verify the color of this wire and its correct location with the circuit diagram? If you just guessed you may be wrong, and if you just stuck it in the connector (assuming that's where it goes) it may not be making a good constant connection. I would get this resolved first before trying anything else.

After that you need to do step 4
"TESTING FOR A SHORT TO VOLTAGE

NOTE: Refer to Test Probe Notice in Service Precautions.

The following procedure tests for a short to voltage in a circuit.

Set the rotary dial of the DMM to the V (DC) position.
Connect the positive lead of the DMM to 1 end of the circuit to be tested.
Connect the negative lead of the DMM to a good ground.
Turn ON the ignition and operate all accessories.
If the voltage measured is greater than 1 volt , there is a short to voltage in the circuit."

DMM= Digital Multi-Meter

Maybe check the hazard switch wiring/connections too:

 

Yes, I traced the broken wire in the schematic and it definitely goes into that connector pack.

I re-checked all the grounds that are related to that circuit and everything tests perfectly.

I'm 99.99% sure it's the BCM. I opened it up, but didn't see any evidence of water. With all the other issues, that's the only thing it could be.



Where's the best place to buy one?

 

Just from experience, but it sounds like you have 12v going through a ground wire. I know it sounds weird, but that's too many things to be going wrong.

If I were you, I would unplug modules throughout the car such as the radio, seat module, door module and try to narrow down.

Electrical problems are always fun.

 

BCM - well that is a logical conclusion. I've read that you can swap your old one for a reman unit @ rockauto, but you have to provide your vin and mileage. Not sure but it may need additional programming in addition to the initial re-learn. May need to check all that out. Good luck.