Large purple wire goes from your ignition switch, which is on top of your steering column, runs through the bulkhead, through the wire loom that runs behind the engine and around the distributor, and down to the S terminal on the Starter. Constant battery voltage goes from the buss bar on the bulkhead above the coolant bottle and down to the B+ terminal on the starter.
Or I can do one better:
Btw, I have the same truck. '89 C1500. Mine has a 5.0L engine. Let me know if I can help further ...
PS, I overlayed the S terminal wire, cause I didn't want to look for the break. I used a 14 gauge wire, a 30 amp slow burn fuse, and it's never given me a problem.
I asked for it in hopes it would help figuring out what is wrong.
I’ll just tell you the story and hopefully you may have some helpful input.
Our truck has been well just not starting or doing anything when we try to start it every so often besides the radio and dash coming on. Sometimes it will start other times it just wouldn’t. Then hours later it might just start right up. We have replaced the starter and battery in the past. This is just a recent issue maybe 3 or 4 weeks? We assumed it was something with the ignition switch. Well Friday I had a hard time starting it and when I got home from work I turned off the truck. I tried to turn it on again and the dash board wouldn’t light up, the radio wasn’t doing anything, and the key pretty much did nothing. The headlights and the light inside were still coming on. We decided to place the ignition switch. Nothing changed… then we noticed that when we touched this wire the dash would light up. The wire was burned? and I managed to start it once when someone was touching it. We replaced the top of that wire and now our dash works. It still wont start or do anything when we try. The lights dim when we try. We tried jumping it….that didn’t work either. I think the fuse starts to mess up again as well.
I don’t have a picture of the inside of my truck but ill use this one I found on google...
that wire that is circled in the picture is the problem. It is a black wire that connects to a red one if I remember correctly.
Okay, have someone hold the key in the crank position and lay under the truck and smack the starter with a hammer. Just give it a tap, don't whale on it and dent it. It's possible that either the starter is having an issue, or there's a wiring issue.
Do you have a test light? Again with a helper, have them hold the key in the crank position, and connect the clamp side of your test light to a good ground (Like a clean spot on the frame, on the negative battery post etc...) and touch the needle part to the small post on the starter with the purple wire going to it. That's the "S" terminal for "solenoid". Your ignition switch sends 12 volts through the purple wire to engage the solenoid on the starter. The solenoid closes two large electrical contacts and through the solenoid, 12 volts and 100ish amps is delivered to the coil in the starter motor.
Do you know what this means? You can take a screwdriver and jump 12 volts directly to the starter "S" terminal and have the starter spin the engine. So, put the key in the "run" position, and use a screwdriver to jump the starter. If the starter works, then you have a problem with getting 12 volts to the starter "S" terminal on the starter.
Hope this helps. If it doesn't make sense lemme know :P
PS: Use a junk screwdriver, sparks can etch out the side of the screwdriver. Also, be careful, it can spark and scare the sh*t out of you if you aren't expecting it!
Last edited by NullHead; 07-10-2012 at 08:38 PM.
Reason: I cannt' speel wery weel.
When we got the ecm we noticed something was wrong with the battery. We had it checked it said we had a bad battery cell. That is when we replaced both. It started right up we drove around (without turning it off) came home and assumed it was fixed. The next day and its back to doing nothing. We tired jumping the battery assuming something messed up. That didnt work. We didnt take it to get tested again. We actually replaced the starter not too long ago... Checked it yesterday and the wire to it was burned. We went to the store. The starter failed. We got a new one put it in and nothing. We have a problem with the battery cell going bad in batteries. It has happened at least 3 times. Not sure if it is related but I am suspecting it is. Any clue to what has caused this? We really aren't sure where to go from here. When it does start it starts fine and runs fine.