IGN-A Fuse Keeps Blowing

[nimrod.sixty9]

Need help tracking down a short as IGN-A fuse keeps popping the second I turn the ignition to crank.

My Chiltons manual says its good for model years up to 98 (says the same for the engine schematic). Can someone with a Haynes or another manual check me?
Im showing positive cable (red) to 40 amp fuse > ignition switch (red) > neutral switch (yellow) > starter solenoid (purple).

Any ides or tips appreciated.

1999 Yukon SLT

 

[Donnie Yukonie]

have you recently done any work to it with the electrical system?

 

[08grey]

Short to ground. The ground won't go away once the fuse is blown. Check each positive wire with a test light for ground ( just the opposite of testing for power just put the alligator clipon positive instead of negative). Once you found the wire trace it. It will be caught on ground somewhere those wires are not so long so once you find out which one it is the elimination process will begin.

 

[nimrod.sixty9]

have you recently done any work to it with the electrical system?

The only thing I changed was the steering sensor.

The first fuse blew when I was putting the dash bezel back in. Ignition was on and shifter was down in first. Replaced fuse and all was good; till now. Now it pops every time.

Short to ground. The ground won't go away once the fuse is blown. Check each positive wire with a test light for ground ( just the opposite of testing for power just put the alligator clipon positive instead of negative). Once you found the wire trace it. It will be caught on ground somewhere those wires are not so long so once you find out which one it is the elimination process will begin.

Much appreciated, but without a proper wiring diagram Ill have no idea what to test.

I pulled the plastic cover off of the steering column and traced the lines I could see. Looked very closely at any point that rubs when the steering column is tilted; all looked good.

According to Haynes, the line I should be looking for goes to the fuse and to the starter relay. Am I right?

Problem is, there are quite a lot more wires coming out of the ignition switch; five to be exact. Then they all go to a black box just next to the switch and out down the column.

Anyone with Alldata? Any other ideas?

 

[08grey]

Test all 5

 

[nimrod.sixty9]

Test all 5

Which leads into a box of 20 more. Which leads to the dash of 1,000 more.

I need a real schematic.

 

[08grey]

You are popping a high amp fuse right? If so its an ignition wire which are the larger 5. This is going to be attributed to your recent work so start backwards and remove whatever you installed and try the ignition. If no luck then leave it removed and test the ignition wires. No diagram is going to be able to help you find a short. You have to test.

A.

 

[nimrod.sixty9]

You are popping a high amp fuse right? If so its an ignition wire which are the larger 5. This is going to be attributed to your recent work so start backwards and remove whatever you installed and try the ignition. If no luck then leave it removed and test the ignition wires. No diagram is going to be able to help you find a short. You have to test.

A.

I know the diagram wont help me find the short, but it will help me know which wires to test (not to mention which ones are hot and which ones are already grounded). I have only recently installed the steering position sensor and HIDs. Ill unplug all and test as soon as I get more fuses.

Speaking of fuses, Im going to the JYard tomorrow and pick up a shit load of fuses and a starter or two. Im starting to think it maybe the starter because it is drenched in oil and all the lines to the starter that I can get to look good.

I followed the line from the starter to the wire loom that's at the back of the block. Opened the entire fuse panel (even the back). Took (broke) off the plastic around the column, and inspected all wires there. All looked new... Starter?

One thing that gets me though; my fuse fails at run, not crank. Or simply fails before I even get to crank. Possible to have a short inside of the solenoid?

---------- Post added at 12:18 AM ---------- Previous post was Yesterday at 11:34 PM ----------

What I have as schematics... Which ones right?

 

[08grey]

You can get a circuit breaker fuse at autozone. Looks just like a fuse but is silver metal and auto resets. That way you don't waist a bunch of fuses. Just get the same amps.

Pull the starter relay and crank it. The starter wire should be black with a white line if I'm not mistaken. It will have power only when you crank otherwise be dead. If it has ground on it now then there is the problem.


Take the alligator clip of the test light. Clip it on power. Now test all the large wires coming off ignition. Any one that has a ground will light. Make note of which ones light and we can go from there. Just do the ignition wires for now and check the starter wire.

 

[nimrod.sixty9]

You can get a circuit breaker fuse at autozone. Looks just like a fuse but is silver metal and auto resets. That way you don't waist a bunch of fuses. Just get the same amps.

Pull the starter relay and crank it. The starter wire should be black with a white line if I'm not mistaken. It will have power only when you crank otherwise be dead. If it has ground on it now then there is the problem.


Take the alligator clip of the test light. Clip it on power. Now test all the large wires coming off ignition. Any one that has a ground will light. Make note of which ones light and we can go from there. Just do the ignition wires for now and check the starter wire.

How I wish to almighty God that I knew about these breakers before frying all those fuses. I think I'm starting to understand how you mean to test, however, I'm hoping to claim victory now...

Last night I was able to get a redneck tow home (nightmare) and finally was able to pull the entire starter. Made sure nothing was touching and reattached battery. Turned the key; fuse lived!

Went to AZ and had the starter tested; passed. Decided to buy and go with the best they had; gold, new, lifetime, etc... Installed and she fires right up every time.

I hope this lasts, thanks for all the help!

 

[08grey]

Nice.

 

[nimrod.sixty9]

Nice.

Well, ****. There goes $100 I didnt need to spend.

Hit a pothole fairly hard; truck dies. Check fuse, and sure enough, its blown.

Try one from heated seats cicuit and instant pop.

Unhooked steering speed sensor and used a 30amp aux fuse; fired right up.



WTF...?

---------- Post added at 07:03 PM ---------- Previous post was at 06:48 PM ----------

Just decided to test again, with the sensor hooked up. Fired right up of course, but this time I moved the wires; it stuttered as I moved them and then died.

Wanted to see if I could isolate it to the sensor by unhooking the sensor, then move the wires. Kept running... Then decided to hook the sensor back up just to see. Kept running...

Why me?

 

[08grey]

When you changed the starter everything was all good ?

 

[nimrod.sixty9]

When you changed the starter everything was all good ?

Yeah, but not anymore.

 

[08grey]

Help me help you. So after the bump you replaced the fuse and it ran okay again?

 

[nimrod.sixty9]

Help me help you. So after the bump you replaced the fuse and it ran okay again?

No, see post 12.

 

[SunlitComet]

is this popping just as soon as you turn on the key? if so then you ignition switch is likely shorting.

 

[nimrod.sixty9]

is this popping just as soon as you turn on the key? if so then you ignition switch is likely shorting.

Normally, yes. But she just died again on the highway. Shook every wire i could get a hold of so I could get it back to the house.

Got it home and still had the bezel off. While running, I tugged on the harness for the light switch and thought I heard arching. Moved it all around and indeed heard it. Just didn't understand how just driving down could short it out, but not moving the wire.

Tugged on it just a little harder and the truck died; same fuse popped. Couldn't see what was shorting, but I suppose I can dissect.

 

[SunlitComet]

no joking hear now. stick a hose up your nose and sniff in those bundle for smell of shorts, arcing or otherwise burnt smells. seriously. you might get luck and find it quicker.