AndyL

G'day all,

Heading out to start chasing down an electrical issue - hopefully someone can point me in the right direction to save a wire by wire chase down of the problem...

Our 90 4runner seems to be having an issue with the power locks. Wife got to work fine, locked up fine. That's where fine stopped. Came out a couple hours later to no ability to unlock the truck and a dead (0.28v) battery. Both front doors - you have to exert key breaking force to the lock - in order to get it up enough to open the doors. Seems like the solenoids are in lock down mode.

Guessing we must have a stuck relay - unplugging the switch pack made no change... Rear doors - locks can be moved easily as expected. Plug the switch pack back in - and rear door locks work as expected - fronts stay in lock down.

Just printing off the FSM wiring diagram, but think perhaps one of you might be able to save me a whole lot of chasing?

yayfortrees

I would check the components first, if you haven't already. Use a multi-meter at the connection to do some diagnosis, rather than start blindly chasing wire.

One place you might be able to check easily before anything would be at the door hinge area, where the wiring runs through the cab to the door. That area has the most flex, therefore the most likely place for a grounded or shorted wire (in theory).

If the relay is stuck on, that would likely be a grounded condition, where it is grounded before the switch. Of course, finding that on a wiring schematic and on the actual vehicle are two different things entirely. Just use that multi-meter to avoid unnecessary work.

Good luck and keep us posted.

AndyL

Still not 100% sure where the problem is - unplugged the 2 electrical connections to the drivers door - but it's still pretty much siezed down. But with that done, the passenger side lock/unlock by key works normally on the remainder of the doors.

yayfortrees

I wonder if you still have a mechanical issue with the lock on the driver side?

That or the mechanical side relies on the elecrical to pull it back into position, and the electrical isn't working in that direction? IDK, I'm just trying to throw some ideas out there.

AndyL

Yeah - gotta be something in the drivers lock solenoid - haven't been able to figure out how I pop that sucker out yet (and been busy fighting with a damn cheby with a sheared heater hose fitting). Solenoid is definitely jambed down - can't get that lock to pop up for anything, looks like it's tucked away behind the latch... Meanwhile once the drivers door is disconnected, no more problems with battery going dead or the rest of the locks operation so...

AndyL

Well - Pulled the solenoid last night... Problem makes more sense now...

4 terminals to the solenoid; the two aluminum terminals are for the solenoid (depending which direction power is applied depends on which direction it fires) the other two... It's a limit switch.

Here's where the fun in mine lies - the little plastic knob on the bottom of the plunger assembly - has a broken side (the side which engages the limit switch) The plunger seems to be welded in place (no amount of forcing will move it; feeding it power - it'll drive move a smidge in either direction. Measured 32 amps in the unlock direction (wired direct to battery). Looks like the limit switch plunger failed, resulting in power being kept on the solenoid - eventually welding it.

yayfortrees

Wow, you don't see that everyday. I would say 32 amps is a tad too much for that.

Now I wonder how much that jewel is going to cost?

AndyL

Yeah, I've got a call in - Parts didn't answer in 18 minutes on hold at my local dealer, so left a message, followed up with an email... Sometimes toyota surprises me with parts $ - sometimes they scare me... But always worth a call first to see, worst case I'll be hunting the wreckers for a replacement, not the end of the world...

Ouch... Just heard back... 2 available in north america - both in california... 695$ canadian. Wreckers here we come...

yayfortrees

Ouch is right! That's flat-out outrageous!

Good luck at the wreckers. Thanks for the update, keep them coming.