1985 Toyota Pickup Electrical Issues - Seeking Advice Symptoms Listed In Thread
 

Hi Everyone,
I've got a 1985 Toyota Pickup SR5 and have been running into some electrical problems lately. Here is a list of issues that I'm seeing, they all started appearing at the same time, so I'm trying to trace down, where a good starting point is.

1. While driving off road (which is daily for us), sometimes when hitting certain bumps in the road, all the power cuts out for a second or two, headlights, dash lights, literally all the power, but the vehicle stays running, and it just comes back on.

2. When using the wipers or the turn signals, you can see the voltage meter on the dash fluctuate with each movement of the blade, or flashing of the turn signals. If I'm not on the gas, the wipers will start to slow to a crawl.

3. Randomly listening to the stereo, I can hear a ground issue. As I rev the engine, the sound increases.

I'm assuming based on the events that trigger the issue, and how it is intermittent, that it is related to a loose or broken wire. The mechanical stuff is a lot easier for me to wrap my head around then the electrical stuff, so I'm just looking for some suggestions as to where I should start the search for the electrical problem. Do any of these symptoms point to a specific place that I should check? Any help would be greatly appreciated.

As a side note, the problems really kicked up after replacing the timing cover and water pump. But I only disconnected the alternator during those installations, and there doesn't seem to be any issues that are obvious to me with the alternator, or the wiring that was removed and reconnected.

If anyone would like pictures of anything to assist in troubleshooting, I am happy to provide them, just tell me what you would like to see and I'll make it happen.

Thanks for taking the time to look, and I appreciate any feedback.

First thing I would check are all your ground wires. Not just look at them, take them off, clean, put some dielectric grease on them and replace whats bad. Grounds are the key of the truck!
Oh, and welcome :wave:

Grounds for sure is you starting place. I didn't even bother to check mine. I replaced the be 3 and for a few more smaller ones. Found so 4/0 welding wire on fleebay and ordered like 25'. So I think I have enough extra to wire up my front winch since its a short run.

If your going to truly check them you will need a multimeter with an alligator clip extension. You need to check resistance through the length of the wire. I cut open some of my old grounds to look and found corrosion 6" up from the connection completely buried in the wire insulation.

Thank you both for your insight. Much appreciated. I rechecked all the grounds, cleaned them off, and used dielectric grease. This resulted in elimination of the ground sound from the speakers, but I'm still experiencing the slow down of the wipers, and the turn signals causing the voltage meter to fluctuate. I will go deeper with the multimeter and check the resistance of the wires tonight. Truly grateful for the assistance and your time.

It's time to check the charging system. 1st, get your multimeter and check the battery when the truck is off, should have about 12.6 volts. Then start the truck and check, should have between 14 and 15 volts, any higher and you have a problem and any thing lower you have a problem. If that all checks out move on to a voltage drop test, just search it online, it's a lot easier to look at a youtube vid then me trying to explain it.
Next would be to check the output of your alternator, but check everything I mentioned 1st
Good luck
Hump

Random doom thought.
Has your truck been parked for a while and this just happened? Any chance you have decent mouse population? They try and invade the cars during winter around here.

1. Electrical problems are hard to diagnose but easy to fix, not always cheap though! Logical tracing of the wiring from the power source (battery and alternator) to the load for interruptions.
2. How old is the battery? Much more than 5-6 years and the average battery starts to lose capacity: this is noticeable with dimming headlights, slowing wipers, slowing defrost fan at idle.
3. Yup, the ground thing.
4. The wiring in your truck is pushing 35 years old. Any wires that flex, even a little could be breaking down and causing this
5. You mention this started after replacing the timing cover, etc. Was this problem there before and has just got worse after this? You may have aggravated some thing, accidentally wiggled something loose. Did you remove the main charging wire? Possibly the post it connects to on the alternator came loose and got twisted resulting in a intermittent short.

With the truck running at idle start wiggling wires and connectors and see what happens. Start at the battery and the fuse links; my guess is you won't need to go much further than that but...keep going then check every thing including the fuses and fuse box terminals. You may have to remove each fuse, clean, inspect and replace. The stereo noise is called alternator whine, caused by poor seating of the brushes on the slip rings of the rotor. How old is the alternator? If you're confident enough you can take the alternator apart and check, clean or replace the brushes (and springs), plus save about 90% the price of a replacement. I've always repaired my own alternators, it really not that hard...getting it off the truck and apart is most of the battle. Easily 90% of bad alternators is simply worn brushes. Also look for the "Radio Frequency suppression capacitors" and see what condition the wiring is in to them. If you have an ohmmeter with them disconnected you will have no circuit through them and will notice the ohmmeter needle swing briefly to zero ohms and then back to infinity. Anything else I'd be suspect of them. These capacitors are those little black boxes about 3/4" x 1/2" x 3/8" with one wire coming from them. If an 85 is anything like an 83 there are three of them, one on the alternator, one by the regulator and one by the battery.

Always start with the cheap and/or obvious stuff before starting with remove and replace troubleshooting...otherwise you could be doing a lot of expensive work when it could just be a loose wire.

+1 to checking wiring first
Also monitor charging voltage at Battery post and at screw terminal / stud (B-Wire) of alternator (LIKE THIS). You should have 13.5 to 15.1 V when engine is running.

Here's an example of that the "capacitor":
https://lh3.googleusercontent.com/vi...=w1266-h712-no

Below is power supply schematic of 1988. 1985 should be pretty close. Probe points before IGN switch for 12V while someone wiggles wires, connections, fuses. With IGN switch on appropriate position, also probe points after the switch for 12V as someone wiggles same.

https://lh3.googleusercontent.com/Wk...g=w886-h712-no

Thank you. I checked the charging system, and that turned out to be A-OK. Will move on to the voltage drop test today.

Car hasn't been parked sitting for a long time, but I live ten miles down a dirt road in the middle of a natural reserve, there are plenty of mice, and while doing some of the other testing suggested by members on here I came across a electrocuted mouse that had been gnawing on some wires. I've since patched those wires up, and got some of the functionality that I'm searching for back, but there is still a ghost in the system, and I'm starting to think that mice are the primary culprits here.

Great advice and I appreciate the extremely detailed response. The battery is an interstate that is less than a year old, maybe 6 months max. Definitely hand some grounding issues, but after rechecking, cleaning all the grounds and applying some di-electric grease the grounds are now working, and I don't hear anything in the stereo anymore. Since I'm still experiencing the drop in voltage using my windshield washers and signals, I'm going to get into the alternator as described above. Thank you very much.

Thank you so much for the detailed advice. I'll be under the hood most of today as I finally got a day off. You guys are all awesome. Thank you infinitely.