Fuses and electrical problem

Tiny
DAVIS0509
  • MEMBER
  • 1989 CHEVROLET SILVERADO
  • 7.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 168,512 MILES
First off I bought this truck last week and didn't give it a good look over.

The transmission is a 400 turbo

1. What amperage is the two battery fuses in the box under the steering column? It has a single wire running from the lower one. When tracing it, it runs to a cylinder under the dash.

2. My running, reverse and dash lights don't come on, everything else works as it should. Any ideas?

3. Installed a generic cigarette lighter into the ashtray, it doesn't work. What relay does it run on? I have the Hanes rebuild book and cant find it.

Thank you in advance for any help you can offer.
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Thursday, September 10th, 2020 AT 10:13 PM

8 Replies

Tiny
4DRTOM
  • EXPERT
Hello Davis,

I attached the fuse block diagram for your truck, give it a review and you should be able to ID the two in question. Go though the diagram and make sure there's not any fuses missing that may be the ones for your dash, running and reverse lights then we can go from there. On your kind of truck in those years I have seen the dimmer switch be dirty on the inside and just moving it a bunch of times the dash lights may start to function again. As for the running and reverse those will be on a different circuit and could be a few things. The switches or poor grounds which is common. The reverse light switch will be on the side of the transmission at the linkage for the gear shifter. Go through and do a visual inspection for broken or corroded wires there at the switch to start with. On this cylinder you speak of can you upload a picture of it? Off hand I would say its the flasher for the blinkers or hazard lights.
Let me know what you find.
Tom
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Thursday, September 10th, 2020 AT 11:10 PM
Tiny
DAVIS0509
  • MEMBER
This is what i'm looking at. The red wire plugged into the battery circuit is running to the black can? Id don't know what the black can is. Looking at the Haynes typical for this year and can't find it. It looks like it was put there aftermarket. Each side has two wires. One side is one black and one red. Other side is one orange and one black. Switch wires look good on transmission. The orange and black side of black cylinder turns into another black and red which ends i'm n a three hole male plug. I'm lost as to what it is. Maybe something with towing? I forgot to mention. There are three towing options installed in the truck, travel trailer, fifth wheel and regular pull behind trailer.
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Saturday, September 12th, 2020 AT 7:34 AM
Tiny
DAVIS0509
  • MEMBER
I have already disconnected the trailer brake control. It had no power and was in the way to where we are so far.
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Saturday, September 12th, 2020 AT 7:36 AM
Tiny
4DRTOM
  • EXPERT
Hello,

Yes, that looks like some sort of trailer braking assistance part. Can you take it down and see is there are any numbers on it or a name?
Tom
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Saturday, September 12th, 2020 AT 8:30 AM
Tiny
DAVIS0509
  • MEMBER
Is there a way to test the ECM? When I put the obd1 it just kept flashing 9 over and over. I waited a good ten minutes to see if it would change but it didn't.
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Saturday, September 12th, 2020 AT 1:30 PM
Tiny
4DRTOM
  • EXPERT
Hello,

Code 9 is the #1 cylinder top center(TDC). What is the truck doing exactly to want to test the ECM? Can you give me clearer picture of what it's doing that not right and I can help out much better? I don't have a good understanding what the problem is except your having a lighting issue.
Tom
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Saturday, September 12th, 2020 AT 9:55 PM
Tiny
DAVIS0509
  • MEMBER
I just recently stepped into this truck blind few weeks ago it does run. I didn't realize that a lot of the electrical had been Frankenstein. I'm slowly working my way through the vehicle trying to remedy one problem at a time.
I was just hoping that the ECM could tell me something other than code nine maybe lead me in a direction to get things fixed and running as they should or installed as I should say as they should be. What was weird is whenever I grounded the test where the OBD1 plugs in. It never flashed code 12 letting me know that the system was functioning properly. I was under the impression at all OBD1 codes are double-digit so it caught me off-guard whenever it through just nine over and over again. I got to 30 amp circuit breakers and plug them in to the fuse panel only to find out there's no power running through the circuit breaker slots, like I said it's a Frankenstein mess and I don't know or even understand what how or why it's like this. I feel as if I'm trying to piece together a puzzle upside down with no way to see the picture the Haynes book has saved my life so far along with your help letting me know where certain things are that are not listed in this book I really appreciate you taking your time with me I just need to get this vehicle up to par so I can drive across America in it back to the East Coast. I'm going to pull the negative lead off the battery so that I can pull the fuse box through and see what the back of it actually looks like. It just doesn't make sense to me as to why there isn't power run to this and how that the vehicle could still properly function.
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Saturday, September 12th, 2020 AT 11:36 PM
Tiny
4DRTOM
  • EXPERT
Okay,

So what performance or electrical failures are you having? Letting me know that is going to be better way to get you on the road.
Tom
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Sunday, September 13th, 2020 AT 9:43 PM

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