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Hello everyone. I've got an issue I think is electrical. While driving the other day, the charge light came on. After parking and turning off the vehicle, I realized that I was unable to start it again. I've tried a few different things since then, without success. I turn the key, without anything happening, no relay click or anything. I am able to roll start the vehicle, and after roll starting I did the traditional alternator test. The voltage on the battery does not change when the vehicle is running. So, I changed the alternator and put a new one in, and also ran a test on the battery. Both are properly functioning, according to the tests. However, the battery still does not charge while the vehicle is running. The charge light remains on. I have tested all fuses and fusible links in both the cab and in the engine bay, and they are properly functioning. To be super clear: After doing the traditional alternator test, it appeared that the alternator was bad, so I installed a brand new alternator. After that, I did the test again and the alternator still appears to not be charging the vehicle. The condition is no-start, no relay click. I was thinking maybe corroded wires in the harness? I'd like to know what you all think. Here is a quick list of some things I've tried:
Parts changed: Alternator is brand new. The two drive belts were replaced and properly tightened.
Parts tested: Battery tested on Autozone machine, tested good. Also attempted to hook up a power pack on the battery in parallel to be sure that the volts/amperes were not too low. Fuses/Fusible links tested.
Electronic parts that work: headlights, hazards. The high beam light will light up on the dash when the brights are on.
Electronic parts that do not work: Dash lights, wipers, radio, turn signals. Alternator is not charging the battery.
Warning lights: Discharge warning light.
Update: I checked a few more systems to test for functionality. The reverse lights are not functioning, the blower motor does not turn on, and the brake lights do not light with the brake pedal depressed. Also, here are some photos:
AM1, AM2, GLOW AM1, and CHARGE fuse all functioning properly, and all other fuses.
Fusible link from GLOW AM1 to Battery positive still has continuity.
Have you checked any of the grounds? They can be the cause of some very frustrating gremlins. Highly recommended to clean them up to bare, shiny metal contacting bare, shiny metal. As RAD would say, should be done every 30 years or so
Others with more electrical knowledge can likely point you in a better direction, but grounds are worth looking at.
Good description of what work and what do not work above! Thanks. Looks like many power branches have issues. STOP buying parts and check wiring one step at a time.
How did you "check" your fuses?
the blower motor does not turn on, and the brake lights do not light with the brake pedal depressed...
Looks like only your power run "A" has good power.
I suggest you measure voltage at power lines A,B,C,D,E,F with Acc on, with IGN on. and report back.
Originally Posted by DJames
The reverse lights are not functioning...Alternator is not charging the battery.
Warning lights: Discharge warning light... turn signals.
Engine fuse supplies backup light, alternator IG wire, and turn signals. Bad IG fuse or wiring would cause this.
I'd like to add a couple of things. If I remove the Engine fuse in the cab, the state of all electrical systems remain the same. No change. So, whether the engine fuse is there or not, all devices behave the same way. Also, I greatly appreciate everyone who's posted on the forum. I'll definitely need to change that ignition fuse to the 7.5A instead of a 30A. I think the PO did that. I'm having trouble understanding how to physically locate A, B, C, D, E, and F. I can see them on the diagram, and I can see how to test voltages across the fuses, since they are labeled, but how do I locate which wires are which, to test them?
Yesterday when I was glancing at my 87 manual it seemed like most roads intersected at the ignition switch.
My recommendation would be to pull the lower dash panel on the driver's side, along with the steering column covers. I'd check for voltage going to the switch, and power out to "ACC" and "ON" depending on key position.
I'd also take a very hard look at the wiring and see if anyone had messed with it in the past. You might have someone's poor wiring repair that came apart. Especially if they had installed a aftermarket alarm, and then removed it.
I gotta thick the source of your problem is somewhere here. Happy hunting and Keep posting
Power source “leg” E has dropped at/after the ignition switch. Explains your alternator issue.
There is something going on with “leg” F because someone stuffed a 30amp fuse where there should be a 7.5amp one.
Both “legs” E & F are derived from the ignition switch. There are no fuses blown and the ENGINE fuse removed does nothing because power is not reaching them.
E leg = ENGINE FUSE 15AMP, dash lights, wipers, turns, radio, and IG from alternator, backup lights
F leg = IGN FUSE 7.5AMP, heater relay and 20amp heater fuse behind your glove box, blower motor resistor, blower motor, heater blower switch, emissions control computer, EACV, evap VSV, fuel cut solenoid, CMH relay, and EBCV (California emissions, less for federal), igniter, ignition coil, distributor.
I'm having trouble understanding how to physically locate A, B, C, D, E, and F. I can see them on the diagram, and I can see how to test voltages across the fuses, since they are labeled, but how do I locate which wires are which, to test them?
One way is to have an 88 factory service manual. Thats the closest way to guaranty the wire colors in wiring diagrams are going to match what your eyeballs will see. Even then there’s discrepancy depending on date of manufacture.
Other than that, note what wire size and color you’re seeing and where, trace them back, and then do a continuity check.
I've checked the points circled below; All of the circuit's fuses have voltage at those points; The values for the ignition switch are in the table below the wiring diagram, they were checked on the back of the switch itself. I too suspect that runs "E" and "F" are particularly not working, after seeing what Rasalibre posted. I do have the FSM for the vehicle, but I don't see wiring diagrams like the one RAD posted. Perhaps there are different FSM's? RAD's diagrams are better than anything I've got. Could it be the ignition switch with those numbers?
The wire running from the battery to the fuse block looks a little fishy to me. Just a picture, so maybe it is just fine, but I see a blue non-factory crimp with what looks like some frayed oxidized wires. I'd pull the sleeve off of that and have a look-see.
If all the fuses and fusible links(including the fusible wire off the battery post) are intact and have power on both legs, and ignition switch has power going in and going out I'm at a loss to explain why so many circuits have failed.
I'd have to fall back on scrutinizing the wiring, specifically where people have made repairs in the past. Under the dash on the driver's side is always a great place to check, along with the driver's kick panel. Under the hood the wires around the battery and driver's side inner fender are a great place to look for futzing.
BTW, If you see these type of connectors I'd highly recommend removing them regardless if they ok at the moment, and soldering/shrink tube the connection.
I've checked the points circled below; All of the circuit's fuses have voltage at those points; The values for the ignition switch are in the table below the wiring diagram, they were checked on the back of the switch itself. I too suspect that runs "E" and "F" are particularly not working, after seeing what Rasalibre posted. I do have the FSM for the vehicle, but I don't see wiring diagrams like the one RAD posted. Perhaps there are different FSM's? RAD's diagrams are better than anything I've got. Could it be the ignition switch with those numbers?
Based on your chart your switch is bad, or you test wasn't accurate..
Run continuity checks on the switch with it unplugged and verify that it's actually switching. Your chart does not show that it does.. In fact it shows your starter, ignition, and accessories are powered with the key in the off position. So bad switch or something connected to things they shouldn't.
(Using the plug/connector numbers are easier to follow than wire colors if that helps anyone but my color blind self.)
That’s a factory diagram. Maybe a somewhat condensed reprint so it doesn’t fold out like the genuine one. If you can ever find the dedicated “Toyota Electrical Wiring Diagrams” book for your year at a reasonable price I’d recommend you grab it. Those are fantastic.
So, I found the issue. Whoever said bad wiring was correct. I checked continuity between these two points:
After checking for continuity, I realized there was none there, when there should be continuity there. So, I started cutting open the wiring harness open beneath the fuse box in the engine bay along the white wire. When I did, I found extra duct tape around a white wire and three wires on the other side. The wires were covered in something blue, and it looked like they had lost their connections. Here's a picture:
After re-soldering those three wires back to the white wire, all the failed electronics came back on-line. Thank you to everyone who helped me with this fix, wouldn't have been able to do it without you!
02-02-2020, 03:36 PM
