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1991 V2500 Suburban losing all electrical power, cont.

eodcoduto

eodcoduto

We could have been closer.
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I bought this Suburban back in November and started daily driving it a couple weeks ago, around 50 miles a day. Three days ago I’m headed to work and the parking brake light comes on and the vehicle stutters for a 2nd then everything was fine. I checked the e-brake and it was good. The next day I’m headed in and the light comes on again and stays on, then after 5 miles I lose all electrical for a little less than 2 seconds, then everything starts back up and I keep going, it does this again 2 miles down the road so I turn around and head home to get the car. It doesn’t do it on the way home. Saturday I checked for shorted wires, prepped and cleaned the ground cable at the battery and the frame, and cleaned the temp sensor ground. The brake light is still on, gets brighter when you apply the parking brake and I checked that switch out, its fine. Other things I notice, the temp gauge is off, sometimes the thermostat opens at 200 sometimes 260 but Ive checked it and the thermostat is good, and the oil pressure gauge stays around 45lbs but will bounce past 60 at times and bounces 60+ at idle after its warmed up.

A long story but I’ll try it again tomorrow, I’m going to pull the starter and see if the hot wire coming off of it is loose, but something is shorting out. I added a 3 wire O2 sensor and ran the hot wire to the 2nd ignition slot on the fuse panel.

Fire away.
 
You need an old priest and a young priest.

Checking the body grounds is a good idea given the number of strange issues. Don't forget the block to the firewall strap and the 2nd negative that is on most battery cables (going to the core support). The gauges flaking out probably points to a poor connection to the engine. I don't see mention of the connections at the starter, but loose or corroded there could give you temporary no-power situations, as all the power in the truck is tied in there.

It might pay off to find the wiring diagram for your year and see what other circuits are tied into the brake light circuit. When you lose a ground or a fuse, it can create a circuit with a bulb in series with something else, causing a dimmer glow.
 
eodcoduto said:
Those are all on my list, a bad ground will ruin your week.
Click to expand...
I was going to say that the brake light comes on when you have a problem in the proportioning valve.
But the gauges acting up has happened to me before when my alternator was going out.
One more thing to check
 
eodcoduto said:
I bought this Suburban back in November and started daily driving it a couple weeks ago, around 50 miles a day. Three days ago I’m headed to work and the parking brake light comes on and the vehicle stutters for a 2nd then everything was fine. I checked the e-brake and it was good. The next day I’m headed in and the light comes on again and stays on, then after 5 miles I lose all electrical for a little less than 2 seconds, then everything starts back up and I keep going, it does this again 2 miles down the road so I turn around and head home to get the car. It doesn’t do it on the way home. Saturday I checked for shorted wires, prepped and cleaned the ground cable at the battery and the frame, and cleaned the temp sensor ground. The brake light is still on, gets brighter when you apply the parking brake and I checked that switch out, its fine. Other things I notice, the temp gauge is off, sometimes the thermostat opens at 200 sometimes 260 but Ive checked it and the thermostat is good, and the oil pressure gauge stays around 45lbs but will bounce past 60 at times and bounces 60+ at idle after its warmed up.

A long story but I’ll try it again tomorrow, I’m going to pull the starter and see if the hot wire coming off of it is loose, but something is shorting out. I added a 3 wire O2 sensor and ran the hot wire to the 2nd ignition slot on the fuse panel.

Fire away.
Click to expand...
By the way, did this start after you added the 3 wire O2?
Maybe you tapped into something that is causing this or, you need to upgrade to a 4 wire for an extra ground. :pimp:
 
It did start after that, but I've unhooked the heating element and the light still comes on. I need to chase some grounds and I'll change the power source for the O2 sensor to see if that helps. Its running decent, but has an odd popping at idle, I'll probably replace the distributor since it has over 200K on it.
 
I re did all of my grounds, and they were in bad shape. That helped starting and the windows alot. Today I put in a new temp sensor and oil pressure sensor, whoever designed the oil switch location needs slapped, and had to pull the distributor to get to it. This fixed an oil leak from the distributor, and when checking base timing it was set around 20 degrees. So I fixed it back to 0, replaced some vacuum lines and hit the road. The brake warning is still on but it runs about 8% better and the popping at idle is gone. Good enough for the girls I date.
 
Are other gauges still affected when brake light comes on?
The brake light only needs key on and a ground to turn on. If you have a short day to another gauge circuit, it could be partially grounding through that circuit.
Ie dim when the problem exists.

If the other symptoms went away with grounds repair and other maintenance. Then the abs module may vary well be this issue
 
Wes Harden said:
Are other gauges still affected when brake light comes on?
The brake light only needs key on and a ground to turn on. If you have a short day to another gauge circuit, it could be partially grounding through that circuit.
Ie dim when the problem exists.

If the other symptoms went away with grounds repair and other maintenance. Then the abs module may vary well be this issue
Click to expand...
The temp gauge still doesn’t act right. At times it will go way past 260 at startup, then act normal once it warms up, with the thermostat opening at 240. But after the first drive of the day it acts right and opens around 210. It runs at 160 on the gauge but it has a 190 thermostat so there is a bad ground or gauge.
 
Yeah probably at the sender, is the Teflon tape, or some other sealer on the sender?
 
The wire has been burned before and there is old electrical tape on it so thats part of it.
 
Well it started acting up again today, it’s raining so I thought maybe water was getting in but I believe its the battery. This happened on my Shovelhead 2 years ago. I bought it and rode back from Knoxsville, about a 250 mile trip. 10 miles from the house it starts breaking up then dies. 0 volts at the battery, after a few minutes its back up to 12. Drove home and it died in the driveway, same thing. Eneded up the battery was shorting out internally.
 
I updated the title, this is definitely an electrical gremlin. I went out to the shop to see if the battery was the issue and had 12.8v at the battery, dome lights are on and head lights all worked. I twisted the keys and nothing, no gauges, fuel pump, starter, heater fan, or anything. So I start chasing wires, and am trying to get to the ignition switch on the column, when all of a sudden the radio comes on and scares the crap out of me. All gauge come on and it fires right up.

So I have power to the fuse box or the dome lights and headlights wouldn't come one. 12v to the alternator, and the junction lugs on the firewall. Since its working now I pulled the fuses and they are good.

Ign fuse good, pulled it and the gauges still work, it cranks.
Dash fuse good, pulled it and the gauges don't work, it starts and cranks.

I'm using this diagram to see what I am missing but I am just not seeing how the fuse block is split and what would make this happen. I know its a short somewhere but where?

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.73-87chevytrucks.com/techinfo/7387CKMans/Wiring/X_9130_1991_GMC_RV_P_Wiring_Manual.pdf
 
I’m fighting the AC duct under the column now to get it to drop down far enough to check those.
 
I have a similar problem on my 91 Burb. On mine the hot wire from the battery didn't run to the starter, instead went to the alternator, then from the Alt to the rest of wiring harness. About half way from the battery to the Alt was a bare spot that was mostly burned in half and arcing on the block.
 
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