2nd gen mystery electrical problem solved + write-up
04-19-2008, 06:34 PM
#41
Registered User
Long-belated thanks to this thread. I've got two Gen2 'Runners, both have issues with the turn signal voltage drop (considerable... lights will dim). I'll be doing this upgrade on both. It's nice when I can sit in a comfortable chair and research a problem instead of digging around with my meter looking for voltage drops 
The ignition circuit is very sensitive. It takes 12v in and multiplies it to the 30,000v (or so) that the plugs require. As such, it is an amplifier. So if you supply it with 12v and it kicks out 30,000v then 13.4V (normal alternator voltage for my truck) is 33,500V. That's a 10% increase in spark voltage. Every volt counts
Man, I did this about a month ago now and as far as I can tell it has made a huge difference. Lots more power bottom end and more pickup.
I dont understand the mechanics behind this but why would it do that? It's an electrical modification. I figured it would remedy any loss I knew I was getting in the electrical system but I didnt think it would be a performance mod at all.
Mike
I dont understand the mechanics behind this but why would it do that? It's an electrical modification. I figured it would remedy any loss I knew I was getting in the electrical system but I didnt think it would be a performance mod at all.
Mike
04-21-2008, 01:07 AM
#42
Registered User
Thread Starter
Nice to hear this info is still helping folks! It drove me nuts until I found the problem and fix. For what its worth - I sold my 4R last month and am now driving an 08 FJ but for as long as I had the fix in place my electrical problems were non existant....never did they return and that blue top optima was as strong as ever.
Sorry about one of the pics missing from my post - I accidentally deleted it from my image host and I never did find another copy of it.
If anybody ever needs help with this mod just email me at romad556 at gmail dot com and I can help you out - I am subscirbed to this thread so any post here should come to my attention pretty quick as it is.
Sorry about one of the pics missing from my post - I accidentally deleted it from my image host and I never did find another copy of it.
If anybody ever needs help with this mod just email me at romad556 at gmail dot com and I can help you out - I am subscirbed to this thread so any post here should come to my attention pretty quick as it is.
Last edited by ROMAD; 04-21-2008 at 01:25 AM.
06-16-2008, 07:55 AM
#44
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ROMAD, thanks for the info! I have been trying to track this down all year! Wasted money on shops to boot. Replaced the cable as you suggested and my electrical problems disappeared.
01-01-2009, 02:37 PM
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Old thread, but wow I've had similar problems coupled with a bad battery. I'm definitely going to have to swap the cable; might as well do all of them while I'm at it. Nice write up romad 
02-23-2009, 08:33 PM
#48
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2nd Gen. reporting in...
Driving home from my birthday dinner...rounding the corner towards home and the Runner dies.....PHEW! At least I made it. Dealer wanted $350.00 for the harness and I paid it...saw the errors of the design going to the 80amp fuse and knocked off the whole wire and replaced it on a perfectly good harness. Ounce of prevention is worth a pound of cure applies here. While I was at it I upgraded the battery with an Optima RedTOP. Now I can run my 100w Hella 500's with out concern and I have already done the headlight wiring upgrade with the relays and I believe they're H4 Silverstars inside the cheap ebay Euro clear headlights. Cheap but they beat the broken ones that came in the 4Runner.
2nd gen owner...done
2nd gen owner...done
10-30-2009, 05:47 AM
#52
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I have had an on going electrical issue with my 1995 4Runner 3.0 SR5 that some of you have experienced as well.
This thread sums up the issue and you will notice that I posted to it and thought my problem was fixed....then it came back as it did for some others in that thread. I finally found the root cause and two methods to fix it.
I have a write up done (no pictures yet) but it's too long to post in here so I will summarize the whole thing for you guys.
Symptoms:
- Radio whine through the speakers (sounds like an alternator whine) with the AC turned on
- When pressing on the brake pedal the volt meter drops dramatically but briefly and if the headlights are on they will noticeably dim or flicker
- When using the turn signals the voltage drops dramatically but briefly
- When using the headlights or flash-to-pass high beams the voltages drops dramatically but briefly
- When attempting to start the vehicle the volt meter may read *very* low (~9V) and the vehicle will not turn over and all accessories barely function. After many attempts at turning key the voltage will return to normal and the vehicle will start as normal.
During any of the above situations it the radio may turn off for a few seconds and the engine may even stall out briefly (!) and that will scare the crap out of you the first time you have it happen to you @ 70 MPH in traffic.
The frustrating part of all this is everything points to a bad ground situation...but it isn't in this case. The other odd thing is due to the slight movement of the cable as you drive over bumps and such the problem may be intermittent.
The problem:
It turns out to be a combination of the factory crimp and too small of a cable gage on the cable that runs from the POS terminal on the battery and goes to the main relay box. This cable attach's to the "slow blow" fuse inside the relay box. This crimp gets weak with normal removal of the battery cables over time. This cable may also begin to heat up and contribute to the situation as well do to the small gage of the cable. If you think this may be your problem you can try tightening up the factory crimp to see if anything gets better. You should verify all your grounds are clean and tight as well as the battery is in tip top shape first.
The fix:
I found two possible methods for this
1) Solder the factory crimp on the battery side of the cable
-or-
2) Replace the cable with a thicker gage cable and solder both ends and replace the factory cable. I did the cable replacement method to kill two birds with one stone.
Identifying the cable
The cable in question runs from the POS battery terminal to the relay box just a few inches away and inside there is the 'slow blow' fuse assembly. The wire attach's to the bottom side of that fuse. The whole fuse assembly will slide out of the bottom of the relay box once you get the relay box off the factory mounts and turned so you can remove the bottom. The factory cable is crimped and soldered on the relay box side so you will have to cut the crimp off if you are going to replace the cable and use on of the screw terminals on that same side to hold the new cable. Its a tight fit this way but it does work.
Modifications
I modified a 19" 6 ga. battery cable from Autozone that had a battery post clamp on one end and a flat terminal with a round hole through it on the other end. I just cut of the battery post clamp end, measuring the length I needed for the new cable (about 10") and soldered on a 6 ga. ring terminal. Then it was just a matter of adding heat shrink and the factory insulation sheath from the original cable to the new cable. Then I used this new cable to replace the factory cable that attach's to the underside of the 'slow blow' fuse assembly in the main relay box. The original flat terminal end on the new cable (the one I didn't cut off the new cable) gets attached to the POS battery clamp just where the factory one connected.
Prices
Since I didn't want to modify my factory part initially, I went to a salvage yard and pulled the factory slow blow fuse assembly and the factory cable for my test modifications.
My total costs were:
19" 6 ga. replacement battery cable (red) - $2.69 @ Autozone
6 ga. ring terminal (3 pack) - $1.99 @ Home Depot
3/8" Heat shrink tubing - $1.99 @ Home Depot
Salvage yard donor parts - $10.00 @ Toyota Heaven
Toyota only sells this cable if you buy the entire POS cable assembly and my local stealership quoted me $137.00 for the POS battery cable assembly complete with the suspect crimp that causes the problem in the first place.
Notes
That should be plenty of info to get you going if you are here searching for a fix. The write up is lengthy and detailed and I don't have pics just yet (or hosting) but if you want it send me a PM and I will email it to you in Word .DOC format. My research turned up the following sites that led to this fix:
Google Groups
www.yotarepair.com (see the section labled 95 4Runner V6 with electrical problem)
Hope this helps somebody because if you have this problem it will drive you nuts.
This thread sums up the issue and you will notice that I posted to it and thought my problem was fixed....then it came back as it did for some others in that thread. I finally found the root cause and two methods to fix it.
I have a write up done (no pictures yet) but it's too long to post in here so I will summarize the whole thing for you guys.
Symptoms:
- Radio whine through the speakers (sounds like an alternator whine) with the AC turned on
- When pressing on the brake pedal the volt meter drops dramatically but briefly and if the headlights are on they will noticeably dim or flicker
- When using the turn signals the voltage drops dramatically but briefly
- When using the headlights or flash-to-pass high beams the voltages drops dramatically but briefly
- When attempting to start the vehicle the volt meter may read *very* low (~9V) and the vehicle will not turn over and all accessories barely function. After many attempts at turning key the voltage will return to normal and the vehicle will start as normal.
During any of the above situations it the radio may turn off for a few seconds and the engine may even stall out briefly (!) and that will scare the crap out of you the first time you have it happen to you @ 70 MPH in traffic.
The frustrating part of all this is everything points to a bad ground situation...but it isn't in this case. The other odd thing is due to the slight movement of the cable as you drive over bumps and such the problem may be intermittent.
The problem:
It turns out to be a combination of the factory crimp and too small of a cable gage on the cable that runs from the POS terminal on the battery and goes to the main relay box. This cable attach's to the "slow blow" fuse inside the relay box. This crimp gets weak with normal removal of the battery cables over time. This cable may also begin to heat up and contribute to the situation as well do to the small gage of the cable. If you think this may be your problem you can try tightening up the factory crimp to see if anything gets better. You should verify all your grounds are clean and tight as well as the battery is in tip top shape first.
The fix:
I found two possible methods for this
1) Solder the factory crimp on the battery side of the cable
-or-
2) Replace the cable with a thicker gage cable and solder both ends and replace the factory cable. I did the cable replacement method to kill two birds with one stone.
Identifying the cable
The cable in question runs from the POS battery terminal to the relay box just a few inches away and inside there is the 'slow blow' fuse assembly. The wire attach's to the bottom side of that fuse. The whole fuse assembly will slide out of the bottom of the relay box once you get the relay box off the factory mounts and turned so you can remove the bottom. The factory cable is crimped and soldered on the relay box side so you will have to cut the crimp off if you are going to replace the cable and use on of the screw terminals on that same side to hold the new cable. Its a tight fit this way but it does work.
Modifications
I modified a 19" 6 ga. battery cable from Autozone that had a battery post clamp on one end and a flat terminal with a round hole through it on the other end. I just cut of the battery post clamp end, measuring the length I needed for the new cable (about 10") and soldered on a 6 ga. ring terminal. Then it was just a matter of adding heat shrink and the factory insulation sheath from the original cable to the new cable. Then I used this new cable to replace the factory cable that attach's to the underside of the 'slow blow' fuse assembly in the main relay box. The original flat terminal end on the new cable (the one I didn't cut off the new cable) gets attached to the POS battery clamp just where the factory one connected.
Prices
Since I didn't want to modify my factory part initially, I went to a salvage yard and pulled the factory slow blow fuse assembly and the factory cable for my test modifications.
My total costs were:
19" 6 ga. replacement battery cable (red) - $2.69 @ Autozone
6 ga. ring terminal (3 pack) - $1.99 @ Home Depot
3/8" Heat shrink tubing - $1.99 @ Home Depot
Salvage yard donor parts - $10.00 @ Toyota Heaven
Toyota only sells this cable if you buy the entire POS cable assembly and my local stealership quoted me $137.00 for the POS battery cable assembly complete with the suspect crimp that causes the problem in the first place.
Notes
That should be plenty of info to get you going if you are here searching for a fix. The write up is lengthy and detailed and I don't have pics just yet (or hosting) but if you want it send me a PM and I will email it to you in Word .DOC format. My research turned up the following sites that led to this fix:
Google Groups
www.yotarepair.com (see the section labled 95 4Runner V6 with electrical problem)
Hope this helps somebody because if you have this problem it will drive you nuts.
11-21-2009, 01:30 PM
#53
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sorry to bring back this thread, i just wanna thank MTL_Runner and ROMAD for writing this and posting it. i have noticed a HUGE DIFFERENCE in doing this mod. my lights dont dim, my volt meter no longer dances when i pound my system. and my amp no longer goes into safe mode. i did also notice better acceleration, not like i gained 10hp or anything...but i no longer struggle going up hills in higher gears. weird?. i think everyone should do this to there 2nd gen.
and if you wondering i drive a 1990 3.0 v6
and if you wondering i drive a 1990 3.0 v6
02-22-2010, 07:05 AM
#54
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Wow, this thread is an oldie but goody! I've only had my 4Runner 3.slow for about 3 weeks and I noticed that going up hills, turning more sharply than a I should at speed or tapping the brakes a bit hard was causing the voltage to go crazy and the truck to stall out sometimes. The local shop said they thought they could get it fixed for around $200, give or take. I can't wait to get off work and give this a try today. Thanks for all you people who've done this and kept this thread alive long enough for me to find it!
02-25-2010, 03:23 PM
#56
Registered User
Thread Starter
Sorry about all the pics being gone guys, I put them up on a host I no longer have access to and they were my only copies. I have helped several people that contacted me by email to do this mod. I have been trying to get someone to take some new pics that shows everything but so far I haven't been too successful in getting new pics.
I haven't had my 4R in years now otherwise I would just take some new ones. Its really an easy mod and I can help anybody that needs it either here or by email.
(EDIT 05AUG10) FOUND SOME OF THE ORIGINAL PICS IN AN OLD EMAIL!! Still missing one but these should help out!
Here is where everything is located under the hood:
Here is what it all looks like with the sub assembly ready for reinstallation:
I haven't had my 4R in years now otherwise I would just take some new ones. Its really an easy mod and I can help anybody that needs it either here or by email.
(EDIT 05AUG10) FOUND SOME OF THE ORIGINAL PICS IN AN OLD EMAIL!! Still missing one but these should help out!
Here is where everything is located under the hood:
Here is what it all looks like with the sub assembly ready for reinstallation:
Last edited by ROMAD; 08-05-2010 at 02:41 PM.
03-02-2010, 02:58 PM
#58
Registered User
Hey all, I just completed my "fix." I call it a fix because I didn't upgrade my wire size. I chose to take this route for 2 reasons. First, I was affraid to take my fuse box appart due to the fact that I didn't want to break it. Second, my little pickup isn't fully loaded. it didn't even come with power steering and it doesn't have any added lights, etc, so I didn't see and reason for the wire to be any biger than what was stock.
However, as you can see in the first picture, there was a little tiny piece of #10 wire between the battery and the fuse box. I don't know why it was there, it just was. I determinded that this was my problem. I put the battery end of the wire under the battery terminal nut because I didn't have the right terminal to do it correctly.
I cut that piece of wire out and spliced in a piece the same size as the factory white wire. This has appeared to cure my problem.
Here are the pictures that I took, I hope they help the next guy.
The little piece of #10 that was spliced in my wire.
This is a picture of the fuse box turned upside down, my thumb is pointing to where the wire in question attaches.
Lastly, this is how mine ended up, for now.
However, as you can see in the first picture, there was a little tiny piece of #10 wire between the battery and the fuse box. I don't know why it was there, it just was. I determinded that this was my problem. I put the battery end of the wire under the battery terminal nut because I didn't have the right terminal to do it correctly.
I cut that piece of wire out and spliced in a piece the same size as the factory white wire. This has appeared to cure my problem.
Here are the pictures that I took, I hope they help the next guy.
The little piece of #10 that was spliced in my wire.
This is a picture of the fuse box turned upside down, my thumb is pointing to where the wire in question attaches.
Lastly, this is how mine ended up, for now.
04-14-2010, 09:22 AM
#60
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I think the splice to the right is a western union splice...
the others look like the old "can't tie a knot, tie a lot"
I too would have been sick of looking at that.
Any concerns on changing the stock wiring:ear
I guess i figure some smart guy had them place that little wire in line to the fuse box..
I'm a dumb guy but want it the same all the way from point to point w/ out splices.
As I see this thread is old and no one is crying about a fire
, I too shall change this wire.
Repo
the others look like the old "can't tie a knot, tie a lot"
I too would have been sick of looking at that.
Any concerns on changing the stock wiring:ear
I guess i figure some smart guy had them place that little wire in line to the fuse box..
I'm a dumb guy but want it the same all the way from point to point w/ out splices.
As I see this thread is old and no one is crying about a fire
, I too shall change this wire.Repo
Last edited by hilandfrog; 04-14-2010 at 02:04 PM.
