electrical issue

[Steve Janz]

Good day...

For information and to set my question up: I have a 1988 FJ62 with a 3B swap (out of a 1985 BJ60).

Of late, I've had intermittent issues with my headlights and heater fan control switch. From time to time when I turn on the heater fan switch, there's absolutely nothing... except that there's some sort of power outage and my digital clock is reset to 12:00. I turn off the fan switch, turn on the headlight switch and then the fan switch again - BINGO - everything works. Today, both the light switch and the heater fan switch both stopped working. When I turn either of them on, there's a strange buzz coming from one of the relays under the dash. Wondering if anybody has had an issue like this? Blinkers, hazards, and brake lights all work fine.

Also, I have a wire coming off of my vacuum canister, runs along the whole firewall and then through and under the dash on the driver's side. As I was rooting under the dash, I discovered this wire that's not hooked up to anything. Should it be? If so, to what?

Thanks to all who might have an idea here... I really don't want to tear the dash all apart to look for a potential ground wire not connected properly... I'll do what I have to do though.

Thanks!

[Granite Grinder]

I know the wire from the vacuum canister will trigger the brake warning light when there is a sufficient drop in vacuum, like none. It's a good thing to have hooked up, you'd be in for quite a surprise if you tried to stop without vacuum assist. It can be done, but i would keep one hand on the e-brake for safety.
Not sure about the other stuff.
GG

[Steve Janz]

so where does the wire plug in... hook up?

[rchalmers3]

Originally Posted by Steve Janz

..... when I turn on the heater fan switch, there's absolutely nothing... except that there's some sort of power outage and my digital clock is reset to 12:00. I turn off the fan switch, turn on the headlight switch and then the fan switch again - BINGO - everything works.

Thanks to all who might have an idea here... I really don't want to tear the dash all apart to look for a potential ground wire not connected properly... I'll do what I have to do though.

Yeah, sounds like a ground alright. There's 2 big underdash ground points on each side of the dash on the A pillars. Go up to the links at the top of this page and download the FSM covering wiring diagrams if you haven't already.

The ground wires are mostly whlte with black striped wires. You should be able to locate the ground circuit common to the places you are experiencing trouble with and the point where it makes chassis ground using the Factory Service information. Once you identify the ground circuit and it's ground point you will be able to devise a test procedure to find your problem.

BTW, it's rare to have a problem in a wire. Problems usually occur at terminals or at loose attachments. I'm betting it's a loose bolt securing the ground wire or something easy, once you find it!

x2 on the vacuum warning. It should tuck into the loom and come in the cabin with the other wires. Look closely at the loom where the wire naturally reaches the loom and see if it was broken off.

Good luck


Rick

[Steve Janz]

Thanks for the info - much appreciated. Could you help me out though... "FSM" - not sure what that stand for or where to find that at the top of the page. Thanks for the help.

[rchalmers3]

Originally Posted by Steve Janz

Thanks for the info - much appreciated. Could you help me out though... "FSM" - not sure what that stand for or where to find that at the top of the page. Thanks for the help.

Sorry: Factory Service Manual

Someone has scanned the manuals for our trucks and has posted them on the internet. As you probably know the information included in these manuals is accurate and much more complete than the alternatives.

Look at the top of the "Diesel Tech and 24 volts Systems" page for a thread with links to these manuals. They are able to be downloaded in .pdf format.

Cheers,

Rick