Electrical gremlin

[Izeloz]

The glove compartment bulb was burned out but does work. The horn works and always did. I believe I found the problem. It was the EA1 connector under the hood. I tracked it down and everything that was having problems goes through that connector before even entering the cab. I was screwing around under the hood earlier and must have bumped the connector and made things kinda work again. I just pulled the connector apart and cleaned it thoroughly with electrical parts cleaner then I lubed it up well with dielectric grease and put it back together. Everything seems to be working well for the time being so I am hoping that was it.

 

[Izeloz]

Update. The gremlin is back. I thought the problem was solved with the di-electric grease and cleaning the connection under the hood. I thought the plug under the hood was to blame again (if it was ever the original problem I have no idea). I unplugged it and plugged it back in firmly. Nothing. Jiggled wires. Nothing. I was listening to my stereo while chopping off the remains of my damaged exhaust and everything just stopped working. I am at a loss. I checked the connections under my dash and everything is solidly "clicked" and clean. Any ideas?

 

[Izeloz]

Well, I don't use my stereo that much and this problem has been more of an annoyance than something essential so I was lazy and really haven't done much more than wiggle a few wires. It's been awhile since anything at all worked on that circuit. Tonight things sorta came back to life and exhibited symptoms that I thought might help troubleshoot the problem. I opened my doors and my dome lights came on. They sorta flickered though and the rear dome light would intermittently go on and off as I played with the door switch. I started the truck up and the clock came on but the light was very dim. I reached up to flip on the maplight and as soon as I flipped the maplight switch the clock shut off altogether without the map light coming on. Turning the switch off brings the clock back to life but switching on a dome light will also kill the clock (resets the clock to 1:00 each time). It's almost as though there is not enough power getting through to power anything more than an LED or small LCD. My stereo did not come on or have any power during this entire episode. Any new ideas that could help shed light on this problem? I would really appreciate any help.

 

[4xoddic]

You're method of installing the aftermarket stereo sounds up to snuff. BUT: how old is that stereo, & what brand? My Wild A** Guess is there could be a lack of electrical contact at the point where the aftermarket plug plugs into the stereo, or the stereo's internal circuits.

The next time you have the dash apart, since you don't miss tunes to the point of aggravation, I would suggest unplugging the stereo AT its aftermarket plug. This would eliminate a possible internal fault which MAY be providing a path to ground far easier for those electrons to find than E1 or D1.

Toyota switching on ground circuits has many positive (+) aspects; unfortunately, also permits many (-) paths in every circuit to find an easier route back to the battery. Consider my experience:

86 Toyota RTE 4X4 Pickup converted by Odyssey in 86 to 21' RV. All circuits to running lights aft of the cab were spliced in (not the up to snuff method you used) under the original cab. Then Scothlok T-taps were used at the rear to route power to tail, brake, parking, running, license plate, etc. EVERY non-OEM light could theoretically become a ground point IF it could find a path back to the battery.

As I replaced taped 16-18 Guage connections with soldered lengths of 12 all the way to the rear, bizarre circuits would show up = wonderful displays of running lights in sync with brake, parking (as should be), flasher, etc. I got similar amazing light shows as I replaced too many T-taps to count.

NOTE: I wasn't actually physically changing any circuits; but I was eliminating alternate paths to ground. All lights worked correctly when I finished, paying an auto electrician would have = counseling sessions $ for most DIYers.

For the sake of Tangential Brevity, I won't go into the 3 months I spent on getting the fuel pump & fuel gauge to work properly. For Beowulf's Sake, I will admit to running every EFI diagnostic in the FSM prior to paying Import Auto (RIP) shop owner to run out of gas. Never underestimate:

1. the drive of an American to reengineer a Toyota switched-ground circuit.
2. the value of fresh gasoline.
3. nor a full tank.

 

[Beowulf]

I would really appreciate any help.

Reread post #17 and study your EWD. The clock behaviour is your clue.

-B-

 

[Izeloz]

I just went and tested all the contacts on my clock connector. The ground is good, the 12V in ACC position is good, the 12V with headlights on is good. My big problem is the constant 12V. At most I tested 4.6 volts. Whenever I switched anything else on the same circuit on the voltage would drop fairly significantly. This constant 12V comes through the dome fuse, relay block 2 and connector EA1. Does it have a relay and, if so, which relay is it?

 

[Izeloz]

Would it be a bad idea to just route new wires from the connector to all these accessories? I just cannot find what the problem is.

 

[Beowulf]

Would it be a bad idea to just route new wires from the connector to all these accessories? I just cannot find what the problem is.

IMHO, it would be a bad idea to route new wires. Toyota builds bullet-proof electrical systems. Based on what you are telling us, yours has a problem between the DOME fuse, the connector point under the dash, the clock, and the IE ground point.

-B-

 

[Izeloz]

I can't find the dang connection point under the dash. There are a few plugs there but none of them look quite like the J3 or J4 connectors in my EWD. I guess I will rip things apart again. It is just starting to get really frustrating not finding the problem. I have full voltage to the connector under the hood. Verify for me if you would that J3 IS the connection where it splits to distribute power to the accessories on this circuit. As a side note, the "key is in ignition" buzzer seems to be on the same circuit but the schematics don't seem to bear that out? Occasionally the buzzer box (which seems to be the same box as the speed control box) will emit an anemic and sad squeal but usually it is silent.

 

[Izeloz]

I found the J3 and J4 connectors. J4 has power (12.4V) when the key is in the on position. J3 has power (11.9V) when the lights are on. The glove compartment light works when the lights are on and the compartment is open. J3 and J4 both have two separate banks of splice points. J4 has yellow wires and black wires that have power when the key is in the on position. J3 has green wires that have power when the lights are on but another bank of white and green wires that never have any power. I don't feel any closer to solving the problem.

 

[Izeloz]

So far this is what I know for sure based on multimeter findings:

1 - IE ground is good because the ground wire for the clock shows strong continuity to any good body ground.
2 - Tail and cigarette circuits/wires are good because they read according to spec (at the clock) whether or not the problem is present.
3 - Dome fuse circuit is good UNTIL at least the EA1 connector under the hood on the fender but the power is NOT making it all the way to the clock or other components.
4 - J4 connector appears good.
5 - J3 connector is good on the green bank of splice points but has no power or continuity on the white and green bank or wires.

 

[Beowulf]

Izeloz,
I really appreciate your tenacity on solving this problem. You are digging deep and doing the right testing. However, I am at a huge disadvantage in that I don't have the EWD for your year and we have found too many differences between yours and my 1997. I don't think that I can be of any more help on this one.

PM Lane or Jon Held or Curtis (CJF) and see if any of them can jump in with some more help. They have the same vehicle that you have.

Good luck and keep us posted.
-B-

 

[scottm]

If we're desperate enough for stabbing in the dark, the hatch hinge wiring is a common failure point in these trucks. Second might be the trailer wiring. Could the dome power wire to the rear hatch be shorting? It's always powered, could cause loss of power in that circuit. I had to replace my hatch ground wire for some fairly odd behavior, I think others have also.

 

[Izeloz]

Beowulf, you have been MORE than helpful on this problem and I owe you bigtime for your time and research on my behalf. If you're ever in the area (Provo, Utah) let me know and I'll take you for some #6's and wheeling. Scott, thanks for the tip. I'll look into it. I just think that a short in a power wire would tend to blow fuses and I haven't been having an issue with fuses. I still have some things to try and look into. Thanks for all the help. IH8MUD is great!

 

[Izeloz]

Still trying to track down the problem. The issue is definitely with the Dome fuse circuit. The EA1 connector under the hood has 12V. At what point does the dome wire split to the different accessories on the circuit? For some reason I am losing all my power between the firewall and the accessories. Is there a splice point I should be looking for? I am getting really frustrated with this problem. I don't want to have to drop the headliner and rip up all the rest of the cruiser to track this down. I already have my dash ripped out. I have removed/unplugged each accessory one by one to see if any of them are the source of the problem somehow. No go.

 

[4xoddic]

The issue is definitely with the Dome fuse circuit. The EA1 connector under the hood has 12V.

How about a current (amps) reading between halves of EA1 with items on that circuit in use? Maybe 2 or more in use at once is dropping current needed to function?

 

[Beowulf]

I don't want to have to drop the headliner and rip up all the rest of the cruiser to track this down.

The issue that Scott had was at the cargo area dome light and I believe his problem was with the ground wire somewhere in the rear hatch area.

If you choose to go that route then look for his thread first. Maybe he can help you find that old thread.

-B-

 

[Lka1988]

If you're ever in the area (Provo, Utah)

You're in Provo?

I'm in Pleasant Grove!

 

[Izeloz]

Let me know if you wanna go wheeling sometime. I found the power flow chart for the dome circuit. Not sure if it will help me (or anyone else) much, but here it is: backdoor switch --> cooling fan --> clock --> door warning light --> fan ecu --> fan relay --> diode --> door switches --> dome lights --> map light --> moon roof relay --> roof motor --> radio --> seat belt warning relay --> amp.

I have removed the engine cooling fan to make way for a second battery. The relay and ecu are still in place. The moon roof still works, but according to the schematic, the power only runs to a buzzer (which doesn't work). The seat belt warning light still lights up, but the buzzer only works intermittently and poorly. I removed the factory amp in my install of an aftermarket deck. Looks like I will just work my way along the flow chart until I come to an obvious problem. I am hoping the backdoor is the issue. Anyone who sees something I don't or has anything to add, please don't hesitate to chime in. Thanks.

 

[Izeloz]

Is it possible that a bad courtesy light switch could be causing these issues?