Hello I have been reading the forum for hours trying to understand my problem.

Our Blazer has started to turn on all the warning lights in the dash cluster at once for just a few seconds at a time. It has happened 6 times in the last week. Twice when I was driving it. I noticed that one or two of them blink, I believe the brake light was one that was blinking.The engine has stayed running everytime so far. Also I could definitely hear a relay click on when the lights came on and off when they went out. I believe the relay I heard is in the BCM (body control module) but am not sure. my wife said that the one time she had the radio on and it when off when the warning lights came on but I did not notice it going off when I was driving it.

I read some post were people were having some similar problems but nothing that helped me find what to check for sure.

I did replace the heater core about 2 weeks before this happened for the first time.

I have replaced the ignition switch twice in the past. First time it was not really bad. The second time the aftermarket switch was engaging the starter in the run position .

My first thought was that it is a bad connection starting up in the ignition switch and acting like it would when you first turn the switch to the run position and the engine is still off. But after reading the anatomy of the ignition switch thread a couple times wasn't sure if one of the 5 connections could cause only the warning lights to cycle and not effect anything else.

I am also after reading not really clear on if the warning lights are indeed controlled by the BCM. It must be capable of turning on all lights in the key on engine off mode through a relay and also turn on only one light at a time if a warning is needed when the engine is running.

Any help in understanding how these lights and the BCM all work together will be greatly appreciated. I searched BCM and read up on it also but so far did not find anything about how it controls the warning lights.

Thank You
Blazeme

 

There's two likely possibilities...
1. The VEHICLE control module has a fault .. If you noticed your engine/power faltering or engine stop, this happens.
- and of course the dreaded bad ignition switch contact.

2. bad circuit in the cluster itself. This would be the likelihood if your engine didnt hesitate.



Known problems in connecting solder joints one level to another as illustrated in the image
This image is representative.. not specific to your problem:

 

I did not even notice a falter from the engine when it happened to me. It seems to be something that is causing a relay to activate the lights with out any loss of power to circuits that power up the engine as it stayed running fine.

As far as a bad circuit in the cluster I would expect a bad solder joint most likely would keep lights from working not cause them to start when they shouldn't. Am I wrong, is there a circuit in the cluster that if open would cause a relay in the BCM to close?

Thanks for the diagram on the cluster, the pick and the quick response.

Blazeme

 

Can anyone tell me if this circuit through the ignition switch could cause my problem if it is loosing connection. Does it send power to run the cluster or a signal to the BCM ?

Edit.
Ok maybe I have found the answer to my own question. It looks like this is the same fuse # 11 shown in the diagram for the ignition switch. So it shows it goes to the cluster and engine controls. Sounds like if it was the cause the engine would be faltering or dieing. So far that isn't happening.



Blazeme