Maybe 1/3 of "Big 3" here...I shall explain.

Intermittent....all affected components do seem to get ground from the "d" ground point (the left kick panel area).

Noticed increase issue yesterday.....audio system playing (nothing monster, just an Alpine CDE-141, no power amp).

Tap the brakes or use turn signal....see dash ammeter kick down, and audio will drop either for a moment or it will entirely reboot the audio head unit (I installed the HU a couple of months ago; wiring to it is confirmed OK).

After stopping to refuel, there was no power at ignition switch, trying 5 times. Checked main fuse panel, nothing out of sorts, didn't really make any adjustments, but trying key again, truck fired right up, and for rest of the trip no ammeter drops with brake or turn signal kick. Electrical system performed fine.

When the system came back up, the clock and radio presets had all reset, an indication of complete loss of power.

I've been searching this issue for a while. I have cleaned kick panel connections, replaced (and cleaned the block) negative cable from battery to block (battery is 2 years old).

Problem acts like loss of ground. Next step will be to replace the block to firewall cable (I suspect that is the ground feed to the "d" bus). Will clean mounting points. Not sure if a short cable with ring connectors is readily available; I see the OEM wire, smaller ga than I would replace with; I may go with a longer cable directly from the battery negative post to the firewall. That should provide a solid ground.

And of course, test.

Am I missing anything in this process? With the intermittent fail-to-start mode I am hesitant to take the rig on the trail and find I am belly up.

Rig is a '94 p/u 22RE; locked; dual cases; 33"MTR; on board air; no other real electrical type mods....

 

just what did you replace with when you changed your ground cable?

I think the factory ones are way under size.

I do not even have a ground going from the engine to the firewall it never got put back on.

I have one to the inner fender one to the steel part of the block and one to the frame.The frame one is kinda a holdover from years of trailer wiring.

The ECM/ECU ground is run also to the ground off the battery .

All my grounds are run with welding cable .

Something is loose someplace or your having charging issues because the main wire from the alternator to the fuse block is cooked from years of thermal cycling

 

So far I have replaced the negative cable from the battery to the block. I used 4ga with a factory crimp battery clamp,and a ring connector. Dremel brushed the block clean where it connects.

Have also run a new 4ga directly from the battery to the firewall where the (yes, undersize) OEM wire was. Cleaned the firewall to shiny bright.

Cleaned the left kick panel ground tie down (this is the "d" bus location as stated in the service manual).

Ran the truck on a test. 40 or so miles just fine,no drops. Then turn signal caused a momentary hiccup in the audio out from the head unit; and then tapping the horn caused the head unit to completely reboot...consistently, although up to this point, tapping the horn caused no ills. Yes, when it dropped I also saw the OEM ammeter (maybe not the best thing, but it's there for a reference) take a hit. When running well, the ammeter would be at an estimated 14.5vdc, and holds steady.

Stopped at about 50 miles, shut off engine; turned key on to accessory position; the whole thing had dumped again, no power for a moment, clock resets, head unit presets reset, the same issue.

I do notice some corrosion at the + cable clamp. The clamp was added to new wire back when. Also 4ga as I recall. I have slack enough to cut it back and get some fresh copper to clamp. Can THIS be causing? I've never gotten a light on the dash, and never had any engine issues when running.

Yes, the rig is 20 years old, original alternator. Thermal? Dunno...it's so danged intermittent. I can't see how any wiring on the head unit harness could cause all this with it working fine most of the time. Sure, I can open the dash and re-crimp everything to it, though would like to try the + cable strip-back first.

Further suggestions more then welcome.

An audio unit glitch isn't life-threatening, but when I stopped yesterday and was completely dead it makes me leery of wanting to put the rig on a trail, then having something fail that it won't recover from.

Trying one thing at a time; I think it's the only way to isolate it. Been an real issue for about 5 weeks so far...

 

It is a personal thing but I think 4gauge is tiny for a ground cable but to each there own.

I have never seen a ammeter in a Toyota yours must be rare.

Did you plug the stereo into the factory harness??

If not where is the switched power hooked to ??

You really need to take some readings at the battery

Do you have the issue if the radio is turned off??

I have seen loose connections in fuse blocks cause these intermittent problems

 

From the way I read your post, you have the stereo hardwired into your truck. Between stereos and trailer lights being hardwired, I have solved more issues by putting the factory plugs back in and then buying adapter kits for trailers and stereos.

I am an electrical idiot so not much help in elelctric, but have seen the contacts on the 80 amp fuse get into bad shape or not making great contact and cause similar problems. It is the main fuse and one that I could see causing you to lose power to everything like you are mentioning. Is the wire that shares the positive cable to the 80 amp to short and when the battery is sliding around causing issues. Something else I have seen as well.

 

Well, I *may* finally have a handle on the situation.

First let me say I must be smoking the cheap stuff, as I truly meant VOLTmeter, not ammeter, although a true ammeter is a fine future mod.

Trying a variety of other things, I ended up completely dead about 60 miles from home. The good thing is it remained dead, as it's easier to trace a constant problem than an intermittent one. With no power, including the interior dome light, I look at the schematic. The dome light gets power right off the battery after the first fusible link, prior to that line entering the main fuse block under the hood. OK. There was 12vdc from the + battery terminal to the engine block (confirmed with voltmeter I had with me). With the line at the FL down the starter solenoid wouldn't work, even though the main + cable feeds the starter. Etc etc etc....well, I have top and side posts on the battery, and about 7 connections via ring terminals on the side post (+ side). I disassembled all of that and used the Dremel/wire brush to clean everything. Power restored, and on the drive back home, no glitches whatsoever. A good possibility I have it under control, but the jury will remain out for some time to further test and prove.

The future plan, as recommended by an associate, is something like the "Blue-Sea" fuse blocks. Add that, and move each of the 7 connections onto their own fused line (yes, each already have in line fuses where needed). I'll feed it with a single (large) + cable from the side post, and make that the only connection to the side post. It should clean things up a lot. For reference, the existing set up has been in place for something like 15 years, so it's not a recent wiring job that was never right. I guess it's been slowly degrading over the last couple of years, as there have been electrical intermittents for some time, they've just gotten worse recently.

As far as my stereo wiring...it uses the factory harness plug, with an adapter onto the Alpine head unit. To adapt to the Alpine harness, I needed to crimp splice some stuff together (although it is possible the wiring was changed by the original owner, spliced off the OEM harness by him; I'd have to get back into the dash to really determine; either way, my crimps have generally been very good, I've installed stereos in many vehicles).

Thanks for tips and support....

 

A little corrosion on a set up with that many ring terminals can cause problems as you found out.

So the little corrosion on the positive battery terminals was the problem to be seen.

The corrosion you can see is bad enough it is the stuff you are unable to really see with just your eyes that gets over looked.