Electrical Gremlins (1 Viewer)

[Demonic92]

Buckle up, this is a confusing story.
To preface, my 91 Land Cruiser has an aftermarket Avital AviStart 6500 keyless entry/remote start unit. It's probably about 25 years old itself but has never given me a problem aside from a valet switch i had to replace. It is tied into a lot of systems with very marginal to ok wire splices under the dash.

I hit the unlock button on my key fob after a successful trip to get food the other day and it just keeps unlocking. Like it unlocked once, and then it was like someone was sitting there continuously pressing the unlock button on the driver's door to piss me off. I start to fumble with the keyfob, thinking the siren alarm is about to go off, and it stops acting up after i press the unlock button a couple times again. I go in to start the car and to my dismay, no HVAC. Absolutely no blower or light on the A/C switch. However, I noticed, that as I turned the HVAC control from "OFF" to any of the fan settings, my doors would unlock. No blower though. Next, I put my foot on the brake and try to shift in to gear. Nope. Shift lock is very locked. I take my foot of the brake... and the doors unlock. Cool, stop light switch is now the door unlock switch. This happens every time i release the brake pedal. I also have no brake lights. I drive home with my doors constantly unlocking because of pressing on the brake pedal and the window down because the HVAC is broken, and as I'm pulling into the garage, HVAC comes back to life and brake lights working normally again. Now I'm happy and park and shut the car off.

Later on, I go to turn on my parking lights while it's parked in the garage. Uh oh. No parking lights. Headlights, yes, but no parking/tail/etc. and then my door locks go haywire again. They just keep unlocking, and the light switch has no effect on the locks or lights after this. I pull the negative terminal off the battery and disconnect the two main 20amp fuses going to the remote start/keyless entry computer thing which is nestled under the dash. Reconnect battery and get a nice spark as the door locks continue to go haywire. Disconnect battery, go to sleep for the night.

Next morning, reconnect battery. No door locks going wild, but also no parking lights still. Parking light switch does not trigger locks. No brake lights, but pressing pedal doesnt activate locks now either. Disconnect battery. Go under dash and pull every plug out of AviStart box and remove unit. Reconnect battery, door locks not freaking out and the parking light switch and stop light switch doesnt trigger them but i also still have no parking lights, brake lights, or HVAC. The door lock switch button itself worked fine and didnt appear to trigger anything else. I hear nothing when i try to switch the lights on, but I did hear and feel the heater fan relay click when i went from "OFF" to "LO" on the HVAC controls. Fan and unit still did nothing, though, and also still no brake lights of course.

All the fuses inside are good, all the fuses under the hood are good. Grounds in kick panels look perfect, visual inspection of what wires I can easily see reveal nothing, and jiggling harnesses and fuse boxes with parking light switch on to see if i could find a short the very lazy way didnt do anything.

I initially thought it could be the AviStart box because it is tied into all those systems... door locks, parking lights, and HVAC system. However, after reading the EWD, i also see that all the affected systems are powered by fuses on the inside fuse box, as you can see in the attached picture.

So at this point, i am assuming i have a hidden short somewhere. Maybe in the driver's door, maybe in the inside fuse box, maybe in one of the under-dash splices for the AviStart box.

I can read the EWD, i am very good at reading. Not sure where to start with diag, however. Checking continuity of wires between connectors, fuses, whatnot? Not really sure how to do that or where to start. I will check to see if the fuses for the affected components have power coming into them when they should, and I'll pull out the fuse box to visually inspect. Other than that, I am lost and I am irritated. Any input, insight, advice is welcome. This is my daily driver and this issue has me all messed up.

Edit: AviStart 6500 install manual/wiring diagram for reference: http://www.directeddealers.com/manuals/ig/avital/avistart6500_install.pdf

 

[jonheld]

I initially thought it could be the AviStart box because it is tied into all those systems... door locks, parking lights, and HVAC system. However, after reading the EWD, i also see that all the affected systems are powered by fuses on the inside fuse box, as you can see in the attached picture.

If the 25 year old AviStart system controls all the systems that you're having trouble with, then there's your answer.

 

[Demonic92]

If the 25 year old AviStart system controls all the systems that you're having trouble with, then there's your answer.

With it removed, it still is being wacky. It would have to be a problem with the AviStart harnesses and/or where they tap into the Toyota harnesses, right?

 

[Racefiend]

I would remove the harness to that avistart box. I'm going to assume they used vampire taps to splice it in because that's pretty much all anyone used back then. Those are terrible, and tend to sever wires. Check all the splice taps, remove them, and inspect the original wires as you remove each one of the avistart wires. Try to pull apart the original wires from each side of the tap point to see if they're severed, and get a look at the copper if you can to see how many strands were cut.

Double check your fuses as well.

I'd start there. Come back if you still have issues and we can walk you through some pinpoint tests.

 

[South Texas 97]

Have you removed the battery from the remote keyfob? on the off chance the button is getting stuck in the down position? this might explain the continual unlocking...

Hidden short or perhaps a grounding issue.

 

[Demonic92]

I went to go fiddle with things just now. Still no parking lights or stop light switch, door locks work fine and not freaking out though. HVAC still doesnt work. I started the car and pressed on the brake and tried to shift into gear and it suddenly came back; lights, stop light switch, HVAC. However i noticed that with the parking lights on and the cluster backlit, when i press the brakes or play with the HVAC control, the gauge lights freak out and dim, doing more so as i turn the HVAC fan higher. Does this seem like a ground issue to you guys?

 

[Demonic92]

And now not even 5 minutes later, after going to grab my EWD, the parking lights and stop lights now don't work again.

 

[gorbilax]

As others have said, the first step to resolving this is to return everything to a predictable, stock state and then troubleshoot from there. Remove any and all non-Toyota harnesses. Inspect all the points where there are aftermarket splices and make sure nothing is damaged. From there, pick a malfunctioning circuit of your choice (lights, locks, etc…) and follow the EWD until you find your issue, My mom’s Sienna had an aftermarket remote start causing this same kind of madness and I didn’t cure it until I totally eliminated the thing.

 

[Demonic92]

As others have said, the first step to resolving this is to return everything to a predictable, stock state and then troubleshoot from there. Remove any and all non-Toyota harnesses. Inspect all the points where there are aftermarket splices and make sure nothing is damaged. From there, pick a malfunctioning circuit of your choice (lights, locks, etc…) and follow the EWD until you find your issue, My mom’s Sienna had an aftermarket remote start causing this same kind of madness and I didn’t cure it until I totally eliminated the thing.

Removing the remote start harness is going to be a crazy amount of work. And i'd like to maintain it if possible. Right now I'm trying to figure out where the problem is in the taillight/tail fuse circuit. Will update as i progress.

 

[Squash]

If your unit lived in a road salt area and/or has been dunked a few times look into the rear quarter panel D/S. Take out the jack and jack hold down.
Reach in and grab the wire bundles and check the condition of the connections.
Ideally the connections are clean and dry inside and not "Green" or cooked.

 

[DivByZero]

The behaviour you've described makes me suspect a melted harness somewhere, where wires have been fused which shouldn't be.

 

[florida95fzj]

Removing the remote start harness is going to be a crazy amount of work. And i'd like to maintain it if possible. Right now I'm trying to figure out where the problem is in the taillight/tail fuse circuit. Will update as i progress.

I just went through this last weekend. Removing the harness revealed other electrical problems I did not know I had. Removing the harness is actually not that bad because the dash pieces come out easily. I don't think it took more than an hour.

Either way, I would get eyes on all of the harness connectors for the circuits that are not working. Odds are you may have to track down several connectors. You'll likely find broken or wet wires. You can also unplug both ends of a specific harness, run an extension wire with alligator clips to your multimeter from one end, and test for continuity on each pin.

 

[gummycarbs]

Removing the remote start harness is going to be a crazy amount of work

It definitely isn't.

It's three screws to remove the lower panel below the steering wheel.

If I'm reading the manual correctly, follow the two yellow wires to the starter wire (black/white on the 80 wiring harness, I believe). Either clip off those wires and bridge them together, or splice the black/white starter wire back together.

Unplug everything else and it should be effectively removed.

You can disconnect each individual alarm/remote start wire from the 80 wiring harness later, if it turns out that disconnecting it fixed your problems. The important thing is to disconnect the plugs from the alarm/remote starter components and reconnect the starter wire.

 

[Demonic92]

It definitely isn't.

It's three screws to remove the lower panel below the steering wheel.

If I'm reading the manual correctly, follow the two yellow wires to the starter wire (black/white on the 80 wiring harness, I believe). Either clip off those wires and bridge them together, or splice the black/white starter wire back together.

Unplug everything else and it should be effectively removed.

You can disconnect each individual alarm/remote start wire from the 80 wiring harness later, if it turns out that disconnecting it fixed your problems. The important thing is to disconnect the plugs from the alarm/remote starter components and reconnect the starter wire.

View attachment 3055878

The remote start harnesses are out and i reconnected the B/W wire to itself at the ignition switch. Starts and runs, but now I'm back to 1991 technology and kind of irritated because I liked the Avital system but know it's just going to break if i spend time to put everything back together.

Regardless, didn't fix my problem, so I started going down the tests for the tail light/parking lights circuit. I have power going from the fusible link to the 3 pin connector above the left front fender, and power comes into the relay panel to the pin that supplies power to the parking light relay. Then I checked continuity between ground and the parking light relay pin that goes to the parking light switch as it is triggered by connecting and disconnecting ground. Checked good. From there a third pin is supposed to supply power to the TAIL fuse and out to the lights, but it doesn't. I bench tested the relay and it clicks on and off, but even though the relay has constant power at the panel and the connection to the switch is good, it doesn't click or do anything when i use the switch. Thus, of course, no power out of the 3rd pin to the TAIL fuse.

In fact... I'm not sure if this would work or is safe, but i used my multimeter probes and an alligator clip to directly connect the 12v power at the relay panel to the pin that goes out to the TAIL fuse, effectively bypassing the relay and switch, and got nothing.

What am I missing???

 

[gummycarbs]

Regardless, didn't fix my problem,

Are your door locks still possessed?

 

[Demonic92]

Are your door locks still possessed?

Door locks were still being possessed after i disconnected the remote start system. The first time it happened, it fixed itself, and then the door locks went haywire again as i tried to turn parking lights on. I disconnected battery and removed power from remote start, reconnected battery, and locks still possessed. Disconnected battery and left overnight, did nothing else, then door lock possession was magically no longer present when i reconnected battery next day. So I honestly can't assign a reason for the door lock thing to anything confidently.

 

[gummycarbs]

Door locks were still being possessed after i disconnected the remote start system.

Was the remote start system functioning as an alarm and remote unlock, too? Have you looked at how it's wired in behind the driver's side kick panel?

 

[Demonic92]

Was the remote start system functioning as an alarm and remote unlock, too? Have you looked at how it's wired in behind the driver's side kick panel?

Yes, alarm and keyless entry as well. Like i said, it's now completely removed. Removed the shock sensor, control boxes, and snipped all the wire splices. There were a few sharkbites but the rest were actually butt connectors. There is still a relay in the door attached to the factory door lock relay but the door locks work fine with it in place still and i doubt that relay would have anything to do with my HVAC and lights.

 

[gummycarbs]

There were a few sharkbites but the rest were actually butt connectors.

What do you mean by "sharkbites" and butt connectors? A butt connector connects the end of one wire to the end of another. The only place that should exist is for that starter wire.

There is still a relay in the door attached to the factory door lock relay

What do its trigger wires connect to?

 

[sunrk]

Solution - remove all central locking and do it the oldskool way with the key to unlock the drivers or pass front door and then manually unlock the rear door behind it if you want to.