1991 RC recovery mission - "Rebel Scum"

[underscore]

I've swapped my ECU and tach caps but I'm sure there are others in there drying out and causing havoc. That might be what failed in my door lock module.

Each time these little gremlins pop up I consider going for a new engine harness and a new EMS now that remote tuning is a thing and I'm not dependant on the local shops, but that's a lot of money to drop and it still leaves all the chassis wiring to cause problems.

 

[Monachopsis]

I've heard that the link ecus solve everything but the wires themselves. They're pricey but hey knock detection, boost controller in built, etc could be nice if you want more kick later.

 

[underscore]

Code 34 is back, yay. The same as before, it randomly kicks in at light load which is really annoying. This time though I got what may be a hint, the speakers started going nuts with popping and squealing even with the volume turned to 0. After a minute it calmed down but there was still a bit of background noise. But when I shut the car off to coast into the driveway and not wake the kids it was crystal clear again. That's making me think I might have a ground issue somewhere. Time to fire up the BGB again.

 

[Roreri]

Code 34 is back, yay. The same as before, it randomly kicks in at light load which is really annoying. This time though I got what may be a hint, the speakers started going nuts with popping and squealing even with the volume turned to 0. After a minute it calmed down but there was still a bit of background noise. But when I shut the car off to coast into the driveway and not wake the kids it was crystal clear again. That's making me think I might have a ground issue somewhere. Time to fire up the BGB again.

Agreed. The little heads up is a sure sign,

 

[underscore]

It was almost comical moving it around to get it into the driveway today, slamming the door and pulling the steering wheel down made the speakers pop lol

 

[Roreri]

It was almost comical moving it around to get it into the driveway today, slamming the door and pulling the steering wheel down made the speakers pop lol

Yeah!

Speaking of pulling the steering wheel down…when the Caldina swap went in, the automatic steering wheel drop solenoid wasn’t wired in, so it has been sitting at the high position ever since. I need to track that down sometime when less pressing matters are on the table.

 

[underscore]

I can't remember if there's a way to manually drop the wheel, but there should be a button on the column to disable it once you get it down.

 

[underscore]

I started poking through things today after spending a bunch of time looking through the wiring diagrams. These cars really have way too many little ECUs in them. Even the stupid dome light is run through an ECU.

The speakers started buzzing any time the key is on so now I'm considering the amp or head unit or wiring. I re-did the adapter harness for the alternator with the new parts and replaced the other half of the alt to main harness plug that previously shattered when I replaced the first half. I found one loose clamp on the AFM to turbo ducting and tightened it down. The main ground cable has a bunch of corrosion at the chassis end so I made up another cable to double it up. The new EFI fuse had a bunch of crud on it already so I replaced it again and cleaned the terminals as best I could. I may need to wrestle the fuse box out and see if I can just replace them. I also learned the higher wattage System 10 amp in the RC has different wiring than the regular one so I have no diagrams for it. The grounds were at least the same colour and they tested okay with the meter. I pulled the amp itself and it looks like the repairs someone did previously are still physically okay but I didn't feel like starting to blindly probe a PCB that complex. At that point I'd probably just put in a new amp.

Tl;dr is no smoking gun but all things that would have caused a problem eventually even if they aren't now, so good stuff to get cleaned up either way.

I don't have the luxury of going for a test drive after each fix and the problem is intermittent so this is a bit stressful because I need the car to be able to do a 2000km trip by Oct 10 and there's 2 weeks in there where I won't be able to work on it. I know I've flip flopped on selling this car a lot over the years but I'm hitting a point where I'm not sure it's viable for me to keep a car that needs a lot more time than I have to give it.

 

[Monachopsis]

I had a new amp put in for like 300. Solved all problems there. as for the the efi fuse that is odd. Never had an issue with mine. The ground corrode like crazy. I use an anode to prevent issues.

 

[Roreri]

I started poking through things today after spending a bunch of time looking through the wiring diagrams. These cars really have way too many little ECUs in them. Even the stupid dome light is run through an ECU.

The speakers started buzzing any time the key is on so now I'm considering the amp or head unit or wiring. I re-did the adapter harness for the alternator with the new parts and replaced the other half of the alt to main harness plug that previously shattered when I replaced the first half. I found one loose clamp on the AFM to turbo ducting and tightened it down. The main ground cable has a bunch of corrosion at the chassis end so I made up another cable to double it up. The new EFI fuse had a bunch of crud on it already so I replaced it again and cleaned the terminals as best I could. I may need to wrestle the fuse box out and see if I can just replace them. I also learned the higher wattage System 10 amp in the RC has different wiring than the regular one so I have no diagrams for it. The grounds were at least the same colour and they tested okay with the meter. I pulled the amp itself and it looks like the repairs someone did previously are still physically okay but I didn't feel like starting to blindly probe a PCB that complex. At that point I'd probably just put in a new amp.

Tl;dr is no smoking gun but all things that would have caused a problem eventually even if they aren't now, so good stuff to get cleaned up either way.

I don't have the luxury of going for a test drive after each fix and the problem is intermittent so this is a bit stressful because I need the car to be able to do a 2000km trip by Oct 10 and there's 2 weeks in there where I won't be able to work on it. I know I've flip flopped on selling this car a lot over the years but I'm hitting a point where I'm not sure it's viable for me to keep a car that needs a lot more time than I have to give it.

I hope the cleanups you did work.

Monachopsis, describe what you mean by an anode? An active current corrosion preventative, correct?

 

[Monachopsis]

I hope the cleanups you did work.

Monachopsis, describe what you mean by an anode? An active current corrosion preventative, correct?

A sacrificial piece of metal (typically magnesium) that corrodes faster than the targeted piece you want to protect. Formally called a sacrificial anode. I dont have any hooked up on the celica at this time but on my daily the TC I have the battery ground with a magnesium washer.

 

[underscore]

Thanks gents.

I bumbled across a copy of the RC amp pinout that I must've saved ages ago. It's all in Japanese but Lens was able to translate enough to confirm which pins are for the door subs. The rest of the speakers I can just power straight off the head unit like I did before when the subs were trashed.

I can't find any 3S fuse boxes for sale, but I have a spare 5S one and the fuses/relays are the same, just in a slightly different layout. I assume to clear the turbo intake piping but I might be able to make it fit in a pinch. Apparently the whole harness may still be available new which is also half tempting. If it's not actually discontinued it's actually pretty reasonably priced.

 

[underscore]

Again slowly cleaning up things I didn't like I decided to dig into the fuel pump only running when jumpered in the diag box. Part of the problem I had before was I had the wrong wiring diagram. I printed out a section of the correct BGB and grabbed my multimeter and went and tested the Circuit Opening Relay and it's wiring. There's no official test procedure but going off of how it looks like it has to work all the wiring and the relay tested fine, which is annoying. I even pulled the starter relay I added and held the key at START and confirmed voltage across both triggers. A bit odd that everything seems fine but I'll try starting it tomorrow and see what happens.

I also decided to replace the burnt out drivers headlight bulb since the low beam stopped working. I assumed it had just been defective and failed early. Nope, somehow the top pin of the socket for the bulb melted. I'm a little concerned about these bits of electrical melting but I'll go buy a higher temp socket and install that I guess.

 

[underscore]

It fired up no problem. I guess I'll run it like this for a bit and just keep my fancy jumper handy in case it's needed.

 

[underscore]

The new door control module showed up so I should have power locks working again soon.

The headlight plug was crunchy. I snipped this off and wired on a new high-temp one.

 

[underscore]

I popped the new door control module in and I have working power locks again which is nice. I figured I should try the speakers with the amp hooked up and the head unit unplugged in case that was the actual cause of the buzzing, since I have to pull the head unit to plug in the module anyways. That was fine so I decided to test the ground for the head unit, which was fine. I plugged the head unit back in and still no buzzing. So no clue what was going on there. Because the intercooler module lives above the door module in the RC I had to unplug and replug that to get it in. Now for some reason the intercooler pump always runs when the key is turned to ON. It's not the worst problem to have since the pump runs anytime you're moving anyways but it's a bit weird.

 

[Roreri]

Hokay!

The way my steed is going through oil if she’s running in a manner that’s not tantamount to suicidal that’s a feat as far as I’m concerned!

 

[underscore]

That's pretty much where I'm at as well haha. As long as it's running okay enough to not explode or get stranded I'm fine. Anything beyond that is just a bonus.

 

[underscore]

Continuing down the list of minor annoyances I took a stab at dealing with the passenger mirror being stuck folded in. Back when it worked I noticed that it didn't move until the drivers side started moving so I figured it just wasn't getting some kind of feedback from the drivers side. I don't have the wiring diagrams for the folding mirrors but I printed the ones for the regular power mirrors and hoped that part would be the same. Unfortunately it looks like the wiring is completely different so no help there.

But I did notice that both sides looked to have the same pinout. So I took a gamble and plugged the passenger mirror into the drivers door and hit the button. Voila, it unfolded. I know that isn't a proper fix but it means I have a mirror again so I'll take it.

 

[underscore]

Continuing down the list of minor annoyances I took a stab at dealing with the passenger mirror being stuck folded in. Back when it worked I noticed that it didn't move until the drivers side started moving so I figured it just wasn't getting some kind of feedback from the drivers side. I don't have the wiring diagrams for the folding mirrors but I printed the ones for the regular power mirrors and hoped that part would be the same. Unfortunately it looks like the wiring is completely different so no help there.

But I did notice that both sides looked to have the same pinout. So I took a gamble and plugged the passenger mirror into the drivers door and hit the button. Voila, it unfolded. I know that isn't a proper fix but it means I have a mirror again so I'll take it.