legacycentral bbs

(Edited to show progress.)

The car still has no turn signals, backup lights, or wipers. The headlights hi/lo, hazards, and dimmer switch all work just fine. Fuses #1 + #2 both blow out. I repaired a couple of bugs along the way but still have these two fuses blowing out to deal with. The wiper motor and combo switch have both been eliminated as variables so far.

vrg63 is offering good debugging advice. Something was shorted and we don't yet know what. The car used to be an automatic but is now a 5spd.

I think the relay left of the glovebox fixes that. I also changed the hazard switch to fix light problems on my car. Also check the parking light switch on the steering column.

It keeps blowing fuses, so I get to find the power wire issue. At least I was able to narrow it down. Not knowing what it is bugs me more than knowing what it is and how to fix it .

When the car got broken into and some stuff got stolen, I think it's the PIAA wiring causing issues. It still has the wiring for the PIAA lights, but no lights.

(PIAA wiring has been removed.)

Yeah, sounds like you got a short in the wiring somewhere causing you headaches.

Maybe try to drop the left fender liner and look in the wiring between the fuse boxes, I have also had problems there. It is very easy for water to get in the wiring if you are missing a clip or screw

I've made some progress, but still haven't fixed it. Both of the same fuses still blow out when they get power. There's a grounded wire somewhere, I think.

I isolated the new combo switch by unplugging everything at the steering column. With just the ignition on, giving power, it still blows the fuses.

This next part is a little harder to describe. I unplugged everything at the fuse box and plugged it all back in one switch at a time. The wide bottom plug gives the turn signals their juice, but doesn't blow anything. With that plugged in, I went for the plug above it. That wide UPPER plug blew the turn signal fuse as soon as I plugged it into the fuse box. The wiper motor is unplugged so I can diagnose one section at a time.

Thoughts? I'm using North Ursalia's wiring diagram for 1991 Leggies.

http://www.northursalia.com/modificatio ... matics.pdf

http://www.main.experiencetherave.com/s ... FSM_Scans/

Internets r fun...

Yes, definitely use the factory wiring diagrams.

You haven't said which fuses blow. You mentioned the turn signal fuse -- which other one blows? The wiper fuse?

But now what's happening? With the wiper motor unplugged you're not blowing the wiper fuse anymore at all?

What do you mean when you say "the wide bottom plug gives the turn signals their juice?" You mean when you plug that one in the turn signals function correctly? What about the backup lights? Hazard lights?

If the wiper fuse doesn't blow when the wiper motor is disconnected, chances are it's a problem in the wiper motor, and that it's independent of the other fuse blowing.

Can you count the number of pins (or spaces where pins would go) each of the connectors you're disconnecting have? That might help us figure out which connector is which when looking at the factory diagrams.

It's starting to sound like it might be a bad hazard switch.

vrg3 wrote:Yes, definitely use the factory wiring diagrams.

You haven't said which fuses blow. You mentioned the turn signal fuse -- which other one blows? The wiper fuse?

But now what's happening? With the wiper motor unplugged you're not blowing the wiper fuse anymore at all?

What do you mean when you say "the wide bottom plug gives the turn signals their juice?" You mean when you plug that one in the turn signals function correctly? What about the backup lights? Hazard lights?

If the wiper fuse doesn't blow when the wiper motor is disconnected, chances are it's a problem in the wiper motor, and that it's independent of the other fuse blowing.

Can you count the number of pins (or spaces where pins would go) each of the connectors you're disconnecting have? That might help us figure out which connector is which when looking at the factory diagrams.

It's starting to sound like it might be a bad hazard switch.

Let me back up, here. I always hated electrical bugs LOL. You gave me some ideas to try, though.

The 15A and 20A fuses both blow. It's the wiper and turn signal fuses. Stepping through things where just one would blow up at a time was where my train of thought was going with it. The fuses for the wipers and turn signals are the ones in question. The hazards also don't blow the fuses. Even when the turn signal fuse goes out, the hazards still work. The back up lights don't. With the wiper motor unplugged, I still blow out the wiper fuse, too.

Keep in mind I had to unplug a lot of stuff and "start from the beginning". With everything plugged in, both fuses blow out the second the car gets power. With everything unplugged, I step through it one plug at a time. That's where I get these other strange behaviors. I unplugged everything at the combo switch and the fuse box both. Just giving it power blows those fuses.

The bottom wide plug I mentioned I believe is a 12 pin, but I'd have to go pull it to look. It's the one next to the large blue wire in the single plug. The plug closest to the fuses is what I plugged in to complete the circuit and blow up just the 15A turn signal fuse.

If there's a better diagnostic procedure, I'm all ears LOL. I know I suck at this part of it, but still managed to get this far. I fixed the driveability problem (signal wire), swapped the combo switch, and got this far with debugging it. The combo switch is new and not the source of the problem. There's a short somewhere or a wire I missed. It's a clusterf*ck in there from a security system, boost controller, stolen ITC, and a turbo timer. I removed the Alpine security system to eliminate that variable, too. Nothing appears to be loose, dangling, or connected wrong. I spent some time in this car before I bought it, and fixed every other little bug it had. This one is driving me bonkers!

Needles. Haystacks. Dammit...

Okay, that's a bit more helpful. But you haven't answered all my questions.

The wide bottom plug gives the turn signals their juice, but doesn't blow anything.

What does this mean? Please be very clear.

I unplugged everything at the combo switch and the fuse box both. Just giving it power blows those fuses.

Just giving what power?

The only way to diagnose a short is to go step by step over the whole circuit. It's a lot harder without an actual wiring diagram. I'll try to help you as much as I can.

The two fuses shouldn't be able to pop at the same time when the key is turned on. Fuse 1 is powered by the ignition circuit but fuse 2 is powered by the accessory circuit.

It makes sense that the hazards would still work since they get their power from a different circuit. That does tell us that we shouldn't be worried about a short in the turn signal wiring.

Is this car an automatic? Because the only place both these circuits intersect is in the automatic transmission shift lock system. If it is an automatic, then let's try unplugging the shift lock control unit. It should be mounted behind the dash kind of to the left of the radio (kind of in the vicinity of the driver's right knee). A little box with a 12-pin black harness connector plugged into it.

Sorry for not being clear on the diagnosis part of things. The car was originally an automatic but has been a 5spd for quite some time.

The plugs I keep talking about are the ones on the fuse box under the left side of the dash. I followed the wires chasing down the circuits before I had the factory wiring diagram handy. I was trying to isolate which circuit might be causing the problem by just plugging the harnesses in one at a time. The bottom wide plug I mentioned is on the fuse box, just above the fuses. With everything else unplugged, I was plugging them in one at a time.

Lets throw that whole logic out if need be, and you can tell me where to start. I went by instinct hunting for frayed wires, loose connections, etc.

That's not a bad way to start. The problem is that it can be confusing because those connectors are used both to feed power into the fuse box and to take power from it.

So it used to be an automatic... By any chance is the shift lock control unit still in the car though? Did you look?

Like I said, the only place that fuse 1's circuit and fuse 2's circuit get near each other is at the shift lock control unit. If that's not it then we probably have two separate problems to track down.

So, fuse 1. If the hazard lights work, then we can pretty safely rule out a short in the turn signal circuit. That leaves just the reverse light circuit. You can unplug the taillights and unplug the reverse light switch. If the fuse still blows, it's a short between the fuse box and the reverse light switch. If not, connect the switch and then you'll know if the short is between the switch and the taillights. Then you can plug the taillights in one at a time too.

Fuse 2. The wiper circuit is much simpler... You said you unplugged the wiper motor -- did you also unplug the washer pump? That probably isn't that relevant because the combination switch should keep the pump from being grounded, but just in case...

Take a look. Let's hope you find a shift lock control unit and you unplug it and the problem goes away.

Well, the big silver control unit is yanked. Is that what you mean? That 4x7 box above the left foot is gone.

If it doesn't short when I first start it up, it shorts when I touch the brakes. Where is the reverse light switch? I hadn't checked any connections on the trans to see if that could be a problem, either.

No, there's another control unit that is just in charge of deciding whether the shift lever should be allowed to move. And, actually, it is connected to the brake circuit too!

It does stuff like make sure you can't shift out of Park unless the key is on and you're pressing the brake pedal.

This is not the TCU mounted under the steering column. This is the shift lock control unit.

vrg3 wrote:It should be mounted behind the dash kind of to the left of the radio (kind of in the vicinity of the driver's right knee). A little box with a 12-pin black harness connector plugged into it.

It looks like this (these are Josh's pictures from his swap):

http://www.surrealmirage.com/subaru/ima ... oller1.jpg
http://www.surrealmirage.com/subaru/ima ... oller2.jpg
http://www.surrealmirage.com/subaru/ima ... oller3.jpg

The reverse light switch is on the transmission body: http://bbs.legacycentral.org/viewtopic.php?t=14263. But I really think the shift lock control unit is where we should be looking.

Got it! It's fixed! The control unit you speak of was removed already and I got to looking at the wiring harness for it. The harness was pinched between the new pedal bracket and the body. I pulled it out, wrapped it up w/ electrical tape, and no more blown fuses! The white/black and white/blue wires were worn through and contacting the metal pedal bracket.

It has everything now! Wipers, turn signals, washer, and backup lights all work perfectly. On to better pursuits of horsepower now! I wouldn't mod it until I got it 100% fixed and legal.

Woo hah! Nice work.