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BOBBYSS
BOBBYSS, Master Technician
Category: Chevy
Satisfied Customers: 17142
Experience:  ASE MASTER CERTIFIED, AA DEGREE AUTO/DIESEL TECH
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Chevy express: 2007 Chevy express van just lost all lights

Customer Question

2007 Chevy express van just lost all lights while driving (dash, interior, turn signals, headlights, brake lights). But still starts and drives.
Submitted: 1 year ago.
Category: Chevy
Expert:  BOBBYSS replied 1 year ago.
Hello, my name is***** for the question. If I am not online when you return please give me some time to get back to you. Most of the time this will occur as the computer tries to save power. It may be shutting systems down. i would check this first. If it is fine then you would need a voltage meter to do this. Let me know if you need more help.
Customer: replied 1 year ago.

Don't have access to volt meter right now. Where would I check the voltage at?

Expert:  BOBBYSS replied 1 year ago.
Does the radio still light up and work as well as the climate control?
Customer: replied 1 year ago.

Climate control works, radio doesn't

Customer: replied 1 year ago.

Climate control works, radio doesn't. Unhooked battery for 10 plus minutes. After hooking back up the, check engine light is blinking, even without ignition on, or key on ignition

Expert:  BOBBYSS replied 1 year ago.
Since you do not have a voltage meter I will have you do a couple of visual tests. In the fuse box under the seat check the CRTSY fuse and locate the CRTSYLT relay. Switch this relay with a similar relay. It may be this fuse or relay. Did you already turn the dimmer knob up to make sure that it was not the issue?
Customer: replied 1 year ago.

Both crtsy fuse and relay under seat are empty. It's not just dash lights, it's ALL lights on whole vehicle.

Expert:  BOBBYSS replied 1 year ago.
Thanks. You do not have the up level package. Did you check the dimmer? If you did then the dimmer itself may be the issue. The other common area of failure is the body control module as it controls these circuits.
Customer: replied 1 year ago.

it is a basic level utility van. Dimmer switch didn't do anything for me.

Where is the body control module?

Expert:  BOBBYSS replied 1 year ago.
The body control module is located under the passenger side of the dash. I would not change it without doing some electrical diagnostics also. Make sure that you check the TBC fuse in the fuse box under the hood.
Customer: replied 1 year ago.

Checked tbc, tbc2, tbc3 fuses in engine compartment. All are fine. The battery seems to have plenty of juice, as it starts the engine without any problem whatsoever. Yesterday afternoon the gauges started going haywire - ABS light, security light, check engine light, gauges not working at times, then coming back to life, etc. I've had similar problems in the past, but had it repaired recently (seemed to be bad/loose ground). Had been working fine for a few months, until yesterday. The gauges and dash lightes indicated above would come and go as I drove, speedometer, gas guage, etc showing nothing, then reading normal - in and out in and out - drove some 400 miles this way. Trying to get home tonight travelling at freeway speeds with the gauges and dash lights continuing to do what they had been since yesterday afternoon. Had not used the headlights a whole lot until tonight, and had been driving for an hour with headlights on and radio. All of a sudden, without any warning, going 80 mph, all lights (including headlights) went out. I managed to tail another vehicle for about 10 miles to get to the next town and gas station where I am now.

The dome lights do come on sometimes, until something else is turned on (or attempted to turn on) then the dome lights go out again.

By the way, I stopped at O'rielly auto parts yesterday afternoon after the gauges started flaking out. They check the battery and alternator in the vehicle. Both said OK, and it showed 14.4 volts at the battery with vehicle running, although the charge indicator gauge in the dash was only showing 9-11 volts. It had been showing 14+ volts until the moment the gauges started freaking out yesterday.

One more clue - when done at the job site today, the van didn't want to start. It turned over fine, but wouldn't start. After several attempts and pumping the gas pedal as I cranked it over, it finally started and we drove for about 90 minutes before these issues started.

Expert:  BOBBYSS replied 1 year ago.
There are a lot of possible issues especially if it occurred first while driving. It can even be the ignition switch though this is not as common. I would definitely check the connections under the fuse box under the hood.
Customer: replied 1 year ago.

Ok, I made it home in the daylight without any thing electrical working other than electronic ignition and fan. No lights, no power windows, locks, wipers, radio etc.

Now with access to a volt meter where should I start?

Expert:  BOBBYSS replied 1 year ago.
Also under seat the is the RAP relay. I would switch this first to see if it is causing this. Switch it with a similar relay. If it still continues then we will continue with testing.
Customer: replied 1 year ago.

Swapping RAP relay didn't change anything. When I have turned off van each time today there is a relay chatter coming from general area you described the bcm being located.

Expert:  BOBBYSS replied 1 year ago.
Check the connections at the BCM then. If it is making this noise then many times it has a bad connection or it is failing internally.
Customer: replied 1 year ago.

Is there a guide for accessing bcm? Don't want to break dash components trying to find it.

Expert:  BOBBYSS replied 1 year ago.
Here are the instructions to remove the panel to access it.
Customer: replied 1 year ago.

Ok, removed it, checked connections, all seem ok. Unplugged and plugged each back in. When removed blue, the relay chatter got faster. When I removed gray, a relay behind climate control began chattering, until I turned climate control off.

Expert:  BOBBYSS replied 1 year ago.
It sounds like the BCM is bad. One other thing to check first though is the wiring connectors under the driver side of the dash. Check under the left kick panel on the far left. Look for signs of wires wearing through near the parking brake or corrosion. Also check the connections near the steering column.
Customer: replied 1 year ago.

wiring seems to be ok in the areas you mentioned. Fiddling with the BCM, it stopped chattering, but still nothing works.

Do have access to the pin callout for this vehicle bcm? 2007 Chevy Express 2500 base model.

I am thinking it's a voltage supply issue that's causing the bcm to malfunction, not necessarily the bcm itself, as headlights, horn, brake lights should not be controlled by the bcm, right? Those should have always live voltage in my mind, not controlled through a module or relay.

I fixed it. It was a grounding issue. The shortest negative wire coming off negative battery terminal to fender wall wasn't making sufficient contact, although it was sufficiently tightened. I had to scour both flange on the end of cable and scratch through the paint on the fender wall. Then all worked like a charm. I don't understand why the other longer wire going down to bottom of engine block was sufficient to start vehicle but not sufficient for much lower amp circuits. Strange.

Expert:  BOBBYSS replied 1 year ago.
That ground should not be that short. I am glad you found the issue. Did you only clean it or did you install a larger cable also?
Customer: replied 1 year ago.

it is oem. I cleaned the wire tab and scrapped seat paint on the fender wall underneath behind where the tab bolts on.

Expert:  BOBBYSS replied 1 year ago.
Great. Did you need any further assistance with this or anything else?