electrical troubleshooting
10-07-16, 11:57 PM
#1
electrical troubleshooting
I picked up a new project last weekend, a '95 M/T SC300 that was equal parts builder and parts car potential. It's been wrecked a couple times, but the engine and transmission are smooth as can be, it drives straight, looks good from most angles, and has a number of upgrades that convinced me to hold onto it.
Aside from fixing where the body got caved in a bit behind the fender, causing the door hinge to be ever so slightly off, the top priority is fixing some sketchy wiring by previous owners. It has a battery drain, non-working turn signals (fuse is okay; haven't checked the flasher module yet), some modification to allow starting it without the clutch pedal depressed, etc.
Attached are four pictures of some of the stuff I've uncovered.
#1: Partially bare green wire w/ silver dots, going from a small white connector at the top left of the fuse box (by the blue and yellow connectors) toward the firewall grommet; you can see it dead center in the photo, right on the edge of the shadow. I taped it up in case it was contacting something and causing a short or power draw.
#2: Top of the picture, what looks like some modified wires coming from that same white connector.
#3: Thick red wire tapped into the main ignition bundle. It runs through the firewall and appears to connect to the starter. I'm guessing this is the clutch pedal override. I have a starter rebuild kit on the way from MyLParts.com, as the starter seemed to be on its last legs. The alternator is new.
#4: Two clipped wires just below the firewall grommet. I'm not sure where they lead to. I believe it's a black and black/white wire, lightly wrapped together at the tip.
Not pictured are two extensions of the footwell light, one leading to an LED in the same vicinity, the other to another LED in the passenger footwell. I removed both of those and taped up where they were tapped in. It's possible that the door being a bit off was allowing interior lights to stay on.
Oh, and the 2-wire white connector to the clutch pedal cylinder was disconnected.
If anyone is familiar with those wires and what they might have been modified for, thanks in advance for pointing me the right direction!
Aside from fixing where the body got caved in a bit behind the fender, causing the door hinge to be ever so slightly off, the top priority is fixing some sketchy wiring by previous owners. It has a battery drain, non-working turn signals (fuse is okay; haven't checked the flasher module yet), some modification to allow starting it without the clutch pedal depressed, etc.
Attached are four pictures of some of the stuff I've uncovered.
#1: Partially bare green wire w/ silver dots, going from a small white connector at the top left of the fuse box (by the blue and yellow connectors) toward the firewall grommet; you can see it dead center in the photo, right on the edge of the shadow. I taped it up in case it was contacting something and causing a short or power draw.
#2: Top of the picture, what looks like some modified wires coming from that same white connector.
#3: Thick red wire tapped into the main ignition bundle. It runs through the firewall and appears to connect to the starter. I'm guessing this is the clutch pedal override. I have a starter rebuild kit on the way from MyLParts.com, as the starter seemed to be on its last legs. The alternator is new.
#4: Two clipped wires just below the firewall grommet. I'm not sure where they lead to. I believe it's a black and black/white wire, lightly wrapped together at the tip.
Not pictured are two extensions of the footwell light, one leading to an LED in the same vicinity, the other to another LED in the passenger footwell. I removed both of those and taped up where they were tapped in. It's possible that the door being a bit off was allowing interior lights to stay on.
Oh, and the 2-wire white connector to the clutch pedal cylinder was disconnected.
If anyone is familiar with those wires and what they might have been modified for, thanks in advance for pointing me the right direction!
Last edited by t2d2; 10-08-16 at 12:04 AM.
10-09-16, 05:27 PM
#2
I'm leaving the battery connected now, as the drain appears to have been tamed. It may just have been an issue with the door not closing properly, after all. Fingers crossed...
I discovered that the DOME (engine bay) and Mirror Heater (footwell; visible in the pics in post #1) fuses were missing. Also the DEF 50A (defroster?) and CDS 30A block fuses in engine bay, but CDS is apparently normally empty (tough to find search matches that aren't CDs, i.e. CD Changer, or "def" short for definitely).
The rear turn signals work now, probably as a result of the DOME fuse. Once I get the front end put back together, the hyperflash should go away and hand signals will be a thing of the past!
My starter rebuild kit will arrive in the next day or two, so if anyone has any thoughts on that thick red wire running to it, that would be the time to address it if ever.
I discovered that the DOME (engine bay) and Mirror Heater (footwell; visible in the pics in post #1) fuses were missing. Also the DEF 50A (defroster?) and CDS 30A block fuses in engine bay, but CDS is apparently normally empty (tough to find search matches that aren't CDs, i.e. CD Changer, or "def" short for definitely).
The rear turn signals work now, probably as a result of the DOME fuse. Once I get the front end put back together, the hyperflash should go away and hand signals will be a thing of the past!
My starter rebuild kit will arrive in the next day or two, so if anyone has any thoughts on that thick red wire running to it, that would be the time to address it if ever.
Last edited by t2d2; 10-09-16 at 09:23 PM.
10-10-16, 09:18 AM
#3
I found some clues...
https://www.clublexus.com/forums/per...ty-switch.html
With a link to: https://www.clublexus.com/forums/per...with-pics.html
That appears to be my thick red wire in question, running from the ignition bundle to the starter, and probably also explains the two clipped wires, one being black/white.
Is there any reason other than remote start to bypass the clutch pedal? Do the neutral safety switches wear out, maybe? At any rate, it's probably something I don't need to trouble myself with right now, as long as it was wired up correctly.
https://www.clublexus.com/forums/per...ty-switch.html
the nutral saftey switch (for an auto) will not allow you to start the car with it in any gear but nutral or park, or(for manual) will not allow the car to start withought the clutch pedal depressed. all it is is a power wire coming from your "ignition switch" or key if you prefer. it comes down to ether the clutch pedal switch for manual or nutral saftey switch in the automatic trans. so the switch connects the starter to power so "grounding it out" will ether do nothing or blow a fuse depending on which end of the wire you ground. in order to bypass the clutch or nutral saftey switch you need to just connect the 2 wires (the one coming from the key and the one going to the starter "s" terminal, the s terminal is the small wire on the starter) together or "jumper" them so its like the switch is not there to begin with. and the starter will work when ever you turn the key to start no mater what postition the clutch or auto shifter is in
in that picture you can see where the red wire goes. there is the black connector there wrapped with foam around it
now if your looking at that connector there should be a black wire with white stripe(this is from the neutral safety switch) your wire that you ran needs to tap into the black with white stripe.
now if your looking at that connector there should be a black wire with white stripe(this is from the neutral safety switch) your wire that you ran needs to tap into the black with white stripe.
Is there any reason other than remote start to bypass the clutch pedal? Do the neutral safety switches wear out, maybe? At any rate, it's probably something I don't need to trouble myself with right now, as long as it was wired up correctly.
10-11-16, 06:45 PM
#4
A few more updates:
Aside from a couple burned out bulbs that I haven't replaced yet, all the lights are working now. After repairing some smashed connectors and damaged harnesses, everything was functional except for the parking lights, side markers, and tail lights. Sure enough, the 7.5A TAIL fuse was blown. I suspect that's related to the bare wire in #1 above, but we'll see if it blows again now that I've taped that up.
The hazard lights aren't working yet. I'll have to backtrack on some of the unneeded wiring I removed from the console area and see if I disconnected something it needs...
The starter rebuild kit hasn't arrived yet -- it was listed as shipping on the 7th, but didn't actually go out until the 11th -- but it may not be needed, after all. I decided to swap in the battery from one of the other SCs, just to have a stronger one to work with for getting the car up and running. To my surprise, it fired right up. So, the battery must have been the issue, not the starter.
When I went up to look at the car, we jumped the battery with a big truck, e.g., a big battery. When I went back up the next day to pick it up, the battery had gone too flat overnight to crank, so we jumped it with the small Subaru battery that was closest. I also brought along a small spare battery. Neither could get it to crank. As I recall, we then swapped in the guy's battery from his other SC and still had to tap the starter to get it to work. That led us to believe the starter was the problem, but the other SC had sat for a bit and maybe that battery was on the weak side, too.
Aside from a couple burned out bulbs that I haven't replaced yet, all the lights are working now. After repairing some smashed connectors and damaged harnesses, everything was functional except for the parking lights, side markers, and tail lights. Sure enough, the 7.5A TAIL fuse was blown. I suspect that's related to the bare wire in #1 above, but we'll see if it blows again now that I've taped that up.
The hazard lights aren't working yet. I'll have to backtrack on some of the unneeded wiring I removed from the console area and see if I disconnected something it needs...
The starter rebuild kit hasn't arrived yet -- it was listed as shipping on the 7th, but didn't actually go out until the 11th -- but it may not be needed, after all. I decided to swap in the battery from one of the other SCs, just to have a stronger one to work with for getting the car up and running. To my surprise, it fired right up. So, the battery must have been the issue, not the starter.
When I went up to look at the car, we jumped the battery with a big truck, e.g., a big battery. When I went back up the next day to pick it up, the battery had gone too flat overnight to crank, so we jumped it with the small Subaru battery that was closest. I also brought along a small spare battery. Neither could get it to crank. As I recall, we then swapped in the guy's battery from his other SC and still had to tap the starter to get it to work. That led us to believe the starter was the problem, but the other SC had sat for a bit and maybe that battery was on the weak side, too.
10-14-16, 08:46 AM
#5
Hazards are working now. They came on as soon as I plugged in the trunk / fuel lid release panel. I wouldn't have thought that completes the circuit, but there you go.
It's actually a bit ironic, as I had left that lower dash panel off to make troubleshooting wiring easier.
It's actually a bit ironic, as I had left that lower dash panel off to make troubleshooting wiring easier.
10-14-16, 10:22 AM
#6
once you have to start tapping the starter it will work on occasion, but randomly it won't.. so if it happens again its probably the starter contacts.
I used to keep a long screwdriver handy to whack mine when it wouldn't cooperate, then after a month it stopped working completely, easy to fix though.
I used to keep a long screwdriver handy to whack mine when it wouldn't cooperate, then after a month it stopped working completely, easy to fix though.
10-14-16, 10:27 AM
#7
We'll see... It's fired up every time with the swapped battery, after refusing to every time with the other three batteries (two that had sat, one that was undersized) and jump starting. The starter rebuild kit arrived yesterday, though, so I've got that on hand if the problem returns.
It is odd, though. The battery that came with it was reading 12V after sitting for a few days -- I was checking for parasitic drain -- but still couldn't supply the juice. Would a weak battery and weak starter work in tandem in that manner?
It is odd, though. The battery that came with it was reading 12V after sitting for a few days -- I was checking for parasitic drain -- but still couldn't supply the juice. Would a weak battery and weak starter work in tandem in that manner?
Trending Topics
10-14-16, 12:03 PM
#8
sometimes on batteries that have been sitting and have bad cells, if they aren't completely gone some of the cells will have just enough juice to hold the voltage while sitting, but as soon as any load is applied they dip down considerably. thats why when you go to get it tested they fully charge it up, but the real test is when they apply the load cause if the cells are done it will dip dramatically when load is applied, and yeah it generally wont turn over but should move the starter a little unless its totally gone. if you get that rapid clicking noise its usually the battery, if you get one solid thunk and nothing happens that means the starter contacts are worn, but still the battery could be bad also.
I have been putting my battery drain issue on the backburner, my battery keeps dying and I cant think of anything that is wired incorrectly in my car cause I did all the wiring. I am starting to suspect the power seats, as my up and down on the seat cushion stopped working years ago... im wondering it its shorted and having a small drain. I am going to unplug the seats and see what happens when I get the time, it sucks to have to keep recharging the battery. I used to use a on off circuit breaker but they keep breaking so I got rid of it, so annoying. if that doesn't work I am yanking out the stereo fuses to see if that helps. Its hilarious that the engines in these cars are so bulletproof, yet the electronics will drive you bat$#!& crazy
I have been putting my battery drain issue on the backburner, my battery keeps dying and I cant think of anything that is wired incorrectly in my car cause I did all the wiring. I am starting to suspect the power seats, as my up and down on the seat cushion stopped working years ago... im wondering it its shorted and having a small drain. I am going to unplug the seats and see what happens when I get the time, it sucks to have to keep recharging the battery. I used to use a on off circuit breaker but they keep breaking so I got rid of it, so annoying. if that doesn't work I am yanking out the stereo fuses to see if that helps. Its hilarious that the engines in these cars are so bulletproof, yet the electronics will drive you bat$#!& crazy
10-14-16, 11:03 PM
#9
if you get that rapid clicking noise its usually the battery, if you get one solid thunk and nothing happens that means the starter contacts are worn, but still the battery could be bad also.
I am starting to suspect the power seats, as my up and down on the seat cushion stopped working years ago... im wondering it its shorted and having a small drain.
I actually swapped three driver's seats between the cars today. I wanted to put my old partial carpet mockup in the M/T Work Truck, since it's awkward to work the pedals with the depth of the bare floor. As long as I was taking the seat out to do that, I might as well remove that most worn seat from the equation. That meant putting in the RX8 seat from the '98, since the '98 is the only one with heated seats (the RX8 seat heater doesn't work; probably the common broken wire) so why put that seat in elsewhere? At least one of the three was light. The other two... No need for weight work today!
if that doesn't work I am yanking out the stereo fuses to see if that helps. Its hilarious that the engines in these cars are so bulletproof, yet the electronics will drive you bat$#!& crazy
10-17-16, 11:14 AM
#10
I was hoping I could reach the electrical connector and just unplug it while its in driving position, its been a while since I have tried to reach under there, hopefully I can do that, not trying to remove the seat at all... maybe there is a fuse for it also haha Ill just start pulling fuses at random and see what happens.
Hope you get it figured out, sounds like you sorted out most of the random wires already. I once used a small battery, it did not last very long but then again I have a phantom drain of some kind.
if you solved all the drain issues, you could definitely use a small battery, or get one of those circuit breakers and disconnect it when sitting or battery tender it... only issue with disconnecting is loosing memory stuff.
Hope you get it figured out, sounds like you sorted out most of the random wires already. I once used a small battery, it did not last very long but then again I have a phantom drain of some kind.
if you solved all the drain issues, you could definitely use a small battery, or get one of those circuit breakers and disconnect it when sitting or battery tender it... only issue with disconnecting is loosing memory stuff.
10-17-16, 12:22 PM
#11
maybe there is a fuse for it also haha Ill just start pulling fuses at random and see what happens.
if you solved all the drain issues, you could definitely use a small battery, or get one of those circuit breakers and disconnect it when sitting or battery tender it... only issue with disconnecting is loosing memory stuff.
Which is ironic, given my fading memory... I completely stripped the stereo and removed the tilt/tele motors and their computer. No stock seats and the memory seat switch isn't hooked up.
10-17-16, 01:21 PM
#12
thanks for the info on the fuse, will look into that (also didn't mean to threadjack but thanks again).
That is convenient that you don't have to worry about the memory stuff, what gets me every time is resetting the radio stations, hvac resetting wouldn't bother me at all.
That is convenient that you don't have to worry about the memory stuff, what gets me every time is resetting the radio stations, hvac resetting wouldn't bother me at all.
10-17-16, 01:51 PM
#13
Ha, no worries, it is an "electrical troubleshooting" thread, after all. Speaking of which, now that I have a SC300, I may have to start following your NA-T Guru thread...
Yeah, radio presets losing their memory is pretty annoying. I wish they had a battery backup or something.
Going back to post #1, picture #2... I was lubing the clutch pedal today, in case that's where the squeaking is coming from (might be the clutch itself, tough to tell), and noticed that the pedal arm brushes by those wires. It might be that they were never modified, just worn from that rubbing. I think I'll wrap them up for a bit more protection.
Speaking of which, now that I have a SC300, I may have to start following your NA-T Guru thread...Yeah, radio presets losing their memory is pretty annoying. I wish they had a battery backup or something.
Going back to post #1, picture #2... I was lubing the clutch pedal today, in case that's where the squeaking is coming from (might be the clutch itself, tough to tell), and noticed that the pedal arm brushes by those wires. It might be that they were never modified, just worn from that rubbing. I think I'll wrap them up for a bit more protection.
10-27-16, 08:25 PM
#15
I poked around a bit more tonight, wanting to get those wires wrapped up and out of the way of the clutch pedal. Of note:
1) The pedal is hitting and stretching them worse than I thought. Something is screwy with the wire routing in there. Does anyone have pictures of that awkward space and how it's supposed to be arranged?
2) In pic #1 in the first post, you can see two thick white/blue wires coming through the firewall. Just as they emerge from the bundle, you'll see a couple marks. One is just an abrasion, while the one on the left is bare metal. I'll have to try following that to see where it goes.
3) In post #1, pic #2, that big white box at the top center of the photo is the main issue. All the wires that are stretched too tight and rubbing on the clutch pedal run to it. Is that a stock box and wire routing? I haven't been able to find photos of it. I probably need to run new wires for some of them so I can extend them out of the way.
(In searching for photos, I discovered why I've never succeeded in pulling down the fuse box once unbolted. No one mentioned that it's full of prong plug-ins on the back!)
That white box is also concealing the FOG and ST-HTR fuses. I was able to get the latter out after much contorting around it and the clutch pedal, but I couldn't quite reach the FOG fuse with a regular length puller to check if it's burned out (fogs don't work). Odd that it had a seat heater fuse, as I didn't think the car was equipped with that option. Maybe someone changed shifter bezels and didn't hook the switches back up.
4) Hazards stopped working again, so plugging in the trunk / fuel lid release panel must have been coincidental to "fixing" them.
1) The pedal is hitting and stretching them worse than I thought. Something is screwy with the wire routing in there. Does anyone have pictures of that awkward space and how it's supposed to be arranged?
2) In pic #1 in the first post, you can see two thick white/blue wires coming through the firewall. Just as they emerge from the bundle, you'll see a couple marks. One is just an abrasion, while the one on the left is bare metal. I'll have to try following that to see where it goes.
3) In post #1, pic #2, that big white box at the top center of the photo is the main issue. All the wires that are stretched too tight and rubbing on the clutch pedal run to it. Is that a stock box and wire routing? I haven't been able to find photos of it. I probably need to run new wires for some of them so I can extend them out of the way.
(In searching for photos, I discovered why I've never succeeded in pulling down the fuse box once unbolted. No one mentioned that it's full of prong plug-ins on the back!)
That white box is also concealing the FOG and ST-HTR fuses. I was able to get the latter out after much contorting around it and the clutch pedal, but I couldn't quite reach the FOG fuse with a regular length puller to check if it's burned out (fogs don't work). Odd that it had a seat heater fuse, as I didn't think the car was equipped with that option. Maybe someone changed shifter bezels and didn't hook the switches back up.
4) Hazards stopped working again, so plugging in the trunk / fuel lid release panel must have been coincidental to "fixing" them.