1989 Jimmy w/ TBI won't turn over

[Zmaster265]

Hey dudes, I need help diagnosing a problem I'm having with my truck. The truck in question is my 1989 GMC Jimmy with a TBI 350 with 173,000 miles backed up by a 700R4. This truck is daily driven.

Ok, now on to my problem: I drove the truck approximately 110 miles from my house to my college (UMR baby!). The truck handled fine the entire way up, power seemed normal, gauge values all stayed acceptable. I got to Rolla and found a nice enough parking spot (I have to park on the street 'cause I don't have a permit yet) and shut her off. I hopped out to make sure i wasn't parked illegally and decided I could pull a bit closer to the curb. So I went to start her up and when I turned the ignition to start it wouldn't turn over. It made a noise like it was attempting to, but no motion. I hopped out, checked the oil and antifreeze, both were fine. Nothing seemed amiss. I then tried again with the same result. I decided to give it a rest, let the truck cool down and not get myself too excited before class the next day. Ok, now today I go to the truck with my fingers crossed and try it again. No luck. I tried to turn it over three times with the same result, and on the third try something blew and I no longer got power to accessories when I turned the ignition to Run. It will no longer even attempt to turn over now.

I observed that the volt meter dropped immedately to zero when I attempted to start the truck. It think what was happening was that power would be cut as soon as I energized the starter. This seems to indicate a short to me, and I hope to god it is something that simple because although a motor swap sounds like a kickass idea to me, I am a poor college student with negative money. Another thing I observed is that when I tried the power door locks I would get a buzzing noise from under the dash. The buzzing comes from a rectangular black box maybe 3"x4"x1" with a white 10 pin plug going to it. This box is located on the driver's side to the right side of the steering column. The buzzing happens as long as the lock button is depressed and has never occured before.

Thanks for reading and please give me your thoughts. This truck is my baby and I am extremely nervous right now.

 

[rogue_shooter45]

Battery

 

[thfonz98]

could be battery, could be grounds also. Killed two starters rather quickly when my grounds were bad.

 

[Zmaster265]

I appreciate the responses guys, but I am fairly sure it is not the battery. I will bring my multimeter out tomorrow to test it, but the battery is in good shape, the water is fine and it has never given me one ounce of trouble before. Also the voltmeter (when I had the key on Acc) read approximately 12.5 volts. The truck did not act like it had a dead or dying battery. There was no cranking whatsoever. It did not slowly crank nor did the starter whine like it wasn't getting enough juice.

I will test it tomorrow, but I am fairly sure it is not the battery, or at least the battery is not the root of the problem.

 

[inscape]

I might be talking out of my butt here, but perhaps the solenoid? Ive had a starter go out on me and it did that, then again I've also had a drained battery before and it did that. Also, i'm sure you already looked at this but is there any corrosion on the terminals?

 

[firefighter184]

Just a scientific wild ass guess here from an incompetent backyard wrencher: Bad starter. If that solenoid craps out, that lack of turning over is a good sign. Does it click click click when you try? Then that's almost definitely it. If you have some sort of short with your starter, I might guess that you shorted the fuse and perhaps drained the battery. Just a guess from a wrenching idiot. Good luck. Try taking off the starter and take it to a Checker. They have a machine there and can test the starter for free.

 

[Zmaster265]

Ok, I've had some time to go work on it now and although it doesn't run yet, I have more information. The battery is fine, the headlights work, the battery terminals and the ground to the intake are shiney and corrosion free. I am not getting power to the Accessory circuits, no voltage was measured when the key was in the Run postion. I was getting voltage out of the Battery circuit on the fuseboard though, so I jumped the two circuits, and i had power to accessories. I then attempted to start it, and just like before, everything went dead as soon as I turned to key to Start.

This time however, there was a blown fuse the Horn/DM 20 amp one. I replaced this with a 25 amp and tried again with the same results, power was cut. But this time the 25 amp fuse did not blow.

I know I have some electrical problem, but I am having trouble pinpointing it. I am getting power to the fuseboard (I tested wires going in 2 hot 10 gauge red wires, and 1 light blue 10 guage ground) but no power from the fuseboard. And even when I was getting power from the fuseboard, any attempt to crank the engine over would kill everything.

I have some guesses as to what the base problem could be.

Starter- It's a Duralast remanufactured unit installed less than 1 yr ago. Maybe the solenoid could be shorted internally?
Ingnition switch- I've heard these go, would this cause my problems?
Short somewhere else?

 

[diesel4me]

try...

See if you can get to the solenoid,and jump the purple wire to the battery positive cable on the solenoid,see if it cranks then..if it does,the starter isn't the problem,its in the wiring..or ignition switch possibly..

You may have corrosion in the fuse box itself..not sure on newer trucks,but the 73-87 fuse boxes are held together by a bolt where it passed thru the firewall--they often corroded inside so bad the terminals the fuses and wires connected to just turned green and dissolved!..I've found many electrical dilema's are there,and not in the harness,like you might be led to believe..might be worth checking into..