Hello all, having an issue on an 86 Chevy K10 truck. Found a poorly made wire connection to the distributor and in the process noticed the feed to the dizzy has 2 volts after key is off? I have since noticed other wires having the same 2 volts. I've been trying to trace it and haven't found the culprit yet. Two weird things I have found is if I pull the "stop" fuse, I assume that's the stop lights, it goes away. While I was trying to get my big butt under the dash to take a look I hit the turn signal switch with my head and it went away?? It also goes away when I move the reverse light switch (on the column by firewall) manually. This switch does not have a neutral safety switch just reverse lights. Where in the heck would this back feed be coming from? Seems with the fuse and turn signal switch it would be in the lighting circuit but why 2 volts at the dizzy? Any ideas? I've been having problems with dieseling and now I'm wondering if this low voltage after key is off has something to do with it. 355 SBC. New to me a year ago. Charges fine, no battery drain. The only wiring I've found that was off was someone put a 4 wire alternator on it and only used one wire. I've since figured out the exciter wire and hooked that up. The other two wires I don't think are needed. Help!
Like EOD Guy suggested, look at the brake switch. If it is adjusted "a bit" to tight it will may cause a slight draw as it is trying to light the stop lights. it's easy to adjust, just loosen the lock nut and unthread it a bit. The plunger should make very light to "just touching" contact with the pedal until it is depressed.
Mark
You already got some good suggestions about the brake switch, but since you have a K10 I have some additional input.
Always check the grounds, and if you have any instrument panel problems (including turn signal indicators, gauges, etc.) its often just the panel ground. The panel ground wire is connected to a post on top of the emergency brake bracket, and if its disconnected you get all kinds of back feed connections when the panel tries to find a path to ground.
If its ignition switch related electrical issues, its often because the small ignition "rack" inside the column has fractured. The rack behind the key switch moves a rod, which runs down the column to the electrical connections for the ignition. If that cheap pot metal rack begins to crack, it will not move the rod accurately and you will get "in-between" connection problems where the switch contacts are not making the right connections for start and run.
Thanks for the suggestions. I will check that out. The only gauge problem I have had is I recently installed the Intellitronix digital gauge set and the speed sensor was getting some interference from somewhere. That was fixed by sheilded wire. The truck is pretty nice and I didn't want to start unwrapping the wire harness. I was hoping someone had a similar issue. I will report back this evening. Thanks again.
Don't have a radio installed. Good thought though. Seems 98% of the wiring is stock and untouched. I have only found a couple hacked up splices. I'm leaning towards the stop light switch. Will find out tonight for sure. Thanks.
Well it's not the brake switch. Still pulling plugs off as I find them. Started pulling the steering wheel off and quit for the night. I pulled all the connections apart at the base of the steering column, wouldn't that rule out anything column related?
75gmc, I don't see a ground on top of the parking brake but way above it on the side wall there is a ground junction point with 3 different ground wires to it. I pulled 2 off and no change but the third is on the bracket bolt and can't get in there to take it off. Looks like the ignition switch is next. Any pointers to taking it out? I made it as far as taking out the turn signal switch. I'm not familiar with the rack you speak of. Is taking out the key switch the way to get to it?
Thanks.
So if you disconnect the steering column connector and you still have a draw...... it's not the column.
The turn mech in the column interrupts the brake lights..... but if you disconnect the column connector that should eliminate that.
The Horn is hot and waiting on a ground. It gets it's ground in the steering column.... again if the connector is disconnected.
The flasher cans are controlled by the column but they can be shorted internal to the fuse block.
If the draw goes away when you disconnect the column connector........... I "de-pin" the column connector, one terminal at a time and narrow down what is actually causing the draw.
I'd remove the green wire from the connector, check for the drain, if the draw is still there, put the green wire back in the connector and try the next one etc...... sooner or later you will find which circuit is responsible for the draw
The rack that was mentioned above should be on the left hand side of the column .... opposite of the key. If your column has a rod that runs thru the column from the key to the actual switch (screwed to the lower part of the column) the rack is the transition from rotary motion (turning the key) to liner motion (moving the rod up and down)
If you unbolt the actual switch from the column and use a sm bladed screw driver to slide the switch thru it's normal motions...... does the draw go away?
I will try that this evening and report back. Being a tilt wheel, I was nervous last night to get too far into the column and have a bunch of springs shoot out or ?? Ive never taken out a key switch before.
I hate to throw a monkey wrench into this thread, but based on you description of the situation so far, I don't believe there is any problem with your truck.
You're saying that the main symptom of this issue is that with the key off, you can read 2 volts in various circuits (coil, turn signals, backup lights - all are circuits that have power when the key is in the RUN position). But if you direct that voltage to a load (such as a turn signal bulb when you activate the turn signal switch) the mystery voltage goes away. Sounds to me like it's just a tiny amount of current leaking through a transistor somewhere (probably the voltage regulator), which is normal and nothing to worry about.
I would recommend testing for parasitic current draw at the battery, and if it's less than about 1-2 mA, I would close the hood and not worry about it.
I was primarily looking into a poor idle issue at first. As I was messing with the distributor i found a VERY poor splice in the dizzy feed wire. I had a volt meter hooked up to the dizzy feed while running and it checked ok. Turned the truck off and saw the meter was still reading 2 volts. I have found several things that stop this 2 volts, but not the cause of it yet.
1.Pull stop fuse
2.turn on either turn signal light with the key off
3.Manually switched the reverse light switch to the on position
I dont see an issue with the 2 volts at lighting circuits, but dont think of it as good on the dizzy wire. Ive had issues with dieseling and curious if this may be at least part of the culprit. I have found this same 2 volts on a couple other odd wires, such as the seat belt buzzer wire. Ive been reading up the last two days on it and I think its making it worse... Some say the tail light bulbs may be 1157 instead of 1156, a lot of people say ignition switch. Sometimes researching makes it worse I think... I have been tracing wires here and there as I come across them, have the steering half apart. Was going to try a new ignition switch since they are cheap. Im semi lost as to where to start looking now. Maybe the wires to key switch? Ive unhooked just about every visible connection and still have 2 volts. Its a toy truck so it doesnt bother me if it sits or get new parts. Probably half the truck is new so may as well start on the other half!!
The voltage has to be coming from an electronic device that has both key on power and full time power wired to it. Since you don't have a radio, that leaves only the voltage regulator. Pull the plug on your voltage regulator, and I'll bet the 2 volts will go away.
No offense to anyone, but I dont really want to get into the poor idle at the moment, LOL... I am curious if the weird voltage to distributor when the key off has anything to do with it?
Dont want to sound like a 'tard here but the voltage regulator is where? Is it the internal one in the alternator? I believe I have already pulled the plug on the alternator and it didnt go away but I can check again tonight. This being an older truck there isnt much to it but I sure havent found it yet... Tonights checks were going to be: install new ignition switch, possibly get into wire side of key switch, check starter wires (already checked for tightness). Do we agree 2 volts to distributor IS bad? Truck runs out pretty good just doesnt idle worth a darn. Have been fighting this for 8 months now...Have 3 brand new carbs at home, freshly rebuilt motor, new intake manifold gasket (just to rule it out) last weekend, pretty much everything attached to motor is new minus alt.
I would absolutely buy a new alt in a heartbeat if it is even possible its backfeeding. I dont like that it is a 4 wire alt and only two wires are used, now anyway. The exciter wire I just now found wasnt hooked up. I know the 2 volts existed before and after the exciter wire thing.
Man, got too late and I gave up for the night...But get this. I'm pretty sure it's the buzzer. Pull the big rectangle buzzer out all voltage went away?!?! There's an orange wire that feeds it hot all the time. Pull that out and it's gone! There's an pink/black wire coming out that I believe is hot with key on, that wire had 2 volts with key off. Makes sense what (forgive me for not having names) you said that it's something with constant power... Now to spend 2 days putting all this darn wiring and dash back together... While you are reading see the pic. Those are the wires to starter. The one wire was cut off like that in the wire loom. Make any sense? I would like to take a sec and correct my previous statement that the wiring looked good...
Could also be a bad ground somewhere looking for a path. the reality is it may have been that way for a long time and may even be a normal occurrence for that model vehicle. It wouldn't be the first time you or me or many others chased a non problem.
Chevy86 - you asked a couple of questions about my post.
Instrument panel ground on your truck may not be on the brake pedal bracket, since they had to change quite a bit of wiring in that timeframe when they started using computer controls. It sound like you found the right grounds.
It does not sound like your ignition rack is broken, and just be glad its working. To get to the rack you have to pull the steering wheel and horn lock plate, and disassemble the entire upper part of the column. Then you install the rack ($12 part) and spend several hours putting it all back together. Google for GM tilt wheel disassembly and you will find several online articles that have pictures of everything.
This article is an example of instructions for pulling apart the TM tilt wheel. Illustrated tilt steering column disassembly. If you scroll down almost to the end, the "rack" is the small part shown just under the words "This one actuates the rod that goes to the actual ignition switch."
Bruce, thanks for the reply. I found out the hard way how to change the ignition switch. It's all back together now. No more 2 volts after pulling the buzzer. Sucks I went through all that just to find out a 2 second fix is all I needed...
On a side note, I've found several cut wires in the process I still need to clean up. The ESC has been bypassed. Do you think it would be wise to take the ESC out completely or just leave it in there? As with the buzzer, there were several (6 I think) wires going to it. I just want to make sure that the ESC isn't interfering with anything else that may be connected to it. The truck has no lock up and has an hei dizzy. I'm probably going to remove the vac switches on the firewall and would like to completely remove the wires. Does anyone know if there are wires to the ESC that go to something else that would be affected by removing it?
Thankya
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