Door Module circuit

[flyboyron]

I have posted here about my dash going crazy when I start it up in the morning when it is cold, (below 50 degrees) with the video.

After having it at the dealer for 5 mornings, they could not figure out what is going on and I picked up the truck.

I kept thinking that when the truck is cold, power from somewhere is shorting to the gauge cluster and causing it to act crazy. I figured if I could isolate the circuit, I could find the source of the problem.

I decided to get a diagram of the fuses (in dash, & engine comp) and pull one fuse every day to see when the problem stops, and that could tell me which circuit could be shorting to the gauge cluster.

Yesterday, I started with Fuse #4 (Door Module). I pulled the fuse and checked the door with the remote and it did not lock or unlock. The passenger side did. I closed the driver’s door and locked it with the key.

This morning I opened the door with the key and as I got in I noticed the gauges (Tach & Speedometer) needles moving up and down erratically (maybe 1/8 inch up and down) like they have been doing since this problem started. I started the truck and the dash backlights came on, the check engine light came on and went off, (like it should) and nothing else in the dash cluster worked. None of the warning lights (yellow or red) were on except the parking brake light. The fuel light was blinking dimly from the backlighting green and then stopped. There was no yellow light for the fuel warning. I sat there and the gauge cluster never worked. No gauges, No DIC either.

I drove to work and noticed the following.

The left turn signal… the lights on the front and rear flashed, but I did not hear the ticking of the flasher and the dash arrow did not light up. The turn signal mirror did not flash either.

The Right turn signal…all the outside lights flashed including the mirror but no sound of the flasher and no green arrow.

The cruise control did not work.

The DIC was dark on both Tach and Speedometer.

I drove to work 20 miles keeping up with the traffic since I did not know my speed.

I arrived at work at 7am and had to leave at 8:30 to go to a clients.

I got in the truck and when I started the truck, the dash came to life and everything worked as normal. Remember, the #4 Door Module fuse is sitting in my center console and was not re-installed.

As I drove to the clients, the turn signals worked normal except the left mirror arrow did not flash. The sound of the ticking flasher and the green arrows were again present.

The cruise control worked.

The DIC was lit up on both sides and everything seemed normal.

 

Is this normal activity after removing the fuse for the door module?

[00Silverado4x4]

Just my opinion but sounds like you have a ground issue somewhere. I'd go around the truck and check all the grounds to make sure they are clean and tight.

[flyboyron]

Ok, I would believe that the mechanic at the chevy dealer would have checked that. They said they checked everything.

I can't do this myself, I wouldn't know where to begin.

 

Now today, I drive the truck to work and lock up the truck and the dash lights, radio, and A/C Heater dash lights are on. They do not turn off no matter what I do.

 

The only way these lights will turn off is after 10 min, the battery drain protection system in the truck turns off all electrical items, and they finally turn off.

 

If it wasn't for that, my battery would be going dead.

 

I am beginning to think it is the BCM.

[flyboyron]

Fantastic.....how does this get posted 3 times?

[00Silverado4x4]

No worries, just a hiccup in the site sometimes. I removed the extra postings.

[Doug_Scott]

Intermittent electrical issues are difficult to locate at best. When a flat rate technician is given a job to repair it, he can only find something if it is happening while he is looking. If he went and spent a few hours going over all the connections would you be willing to pay the hourly rate? Even if he could not locate the issue?

 

As I posted in your original thread(not sure why you started a new thread for this), this could be a cold solder connection problem. Unless your or the technician happens to check that specific wire while it is happening, it may very well fix itself(as it does now) and not be able to be located. I can understand your frustration, and can also understand the technicians. I have had a few of those jobs over the years, the ones where I spent many hours trying to locate an issue, with the customer only actually having to pay for the last trip when I finally located the intermittent open circuit(short circuits blow fuses, easy to find). I got my .6h pay to fix it. Got zero pay for the many hours trying to unsuccessfully reproduce/locate it. After a couple of those, you start not looking if it is not present at that time.

 

When you get may issues with many different circuits like you are getting, it is almost always a bad ground connection somewhere. You need to locate the one common thing in all the circuits. For example, on a 1973 Chrysler Imperial, there is a single ground connection in the dash for 5 ground wires. If that connection is loose, when you apply the brakes the wipers will sweep once occasionally. Open the drivers door, the right signal in the dash will light up. Honk the horn, and the power antenna retracts. Luckily I was not flat rate when given that job. I was a 3rd year apprentice at the time. Still had that "no car will beat me" attitude. Ended up taking half a turn of a 3/8ths wrench to fix, plus 4 hours to put the dash back in. No one in the shop had ever experienced that before. Not even the mechanic that started there after coming home from Europe after WWII.

[flyboyron]

Thanks Doug. I reinstalled the Door Module fuse and everything works normal again.

Since I have to drive it everyday, I will for now just leave it until something acts up more often or quits and gives the mechanic something to look for. I am going down tomorrow to take my wife's car down for some recall work and will ask them what they would charge to check all the grounds on the truck.

 

Heck, I am already into this $800.00, what's another couple of hours labor if I can get it fixed now.

 

Thanks again.