Car not starting randomly? READ THIS (30 Amp Starter Relay Mod)

3p141592654

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So, given its old H/W you located the source of the voltage drop in the loop by doing the basic test procedures outlined in this thread, and therefore isolated the issue to the ____?
 

Satan

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...isolated the issue to the Starting circuit. Used the Starting (7M-GE) & Starting (7M-GTE) info, in the Electrical Wiring Diagram section of the TRSM. :icon_bigg
 

Satan

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And if the ignition switch is the root cause of the problem? Do you know that it isn't?
It's working right now. If it is the root cause, it's not behaving like it. If the circuit fails again, that is where I will start. I do happen to have several spare/used switches available, if needed.

This is what I did... Maybe a visual will help. Let's stop arguing... If someone wants the root cause, they know what to do. If someone wants to replace their circuit, here's an example of what I did. If'n you have the issue, read the thread and do what you want (even if it's not necessarily 100% what some people would recommend -- it's your car).

Startercircuit.png

Just a basic diagram/example. I have also addressed my alarm and NSW signals (auto chassis, now w/R154).
 
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3p141592654

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LOL. The solution is not to find the source of the problem, but to add relays, and now wire to mask the problem. Case closed. Next...
 

Satan

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Not masked. Problem with anything stock, between the 2 end points in the pic in post #203, have been removed from the equation (replaced by newer components, along a different route/path).
 

Dirgle

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The thing that worries me here is that you have removed only one wear item from the circuit, the starter relay, which I would assume you have already tested so that wasn't the issue. The other two are the IGN switch and the starter contacts. Both of which could still be an issue. Like Pi said, you might only be masking the problem. It could very well come back. Also the factory starter relay only exists to give the clutch switch and theft deterrent computer easy disable control over the start circuit. The addition of a relay in a bypass circuit is pointless, ST1 was designed to carry both the inductive and switched loads of the start circuit. Unless it's to boost power to the system adding a relay to a bypass circuit merely adds failure points where there doesn't need to be any. And if the relay was added to boost power to the start circuit, then that indicates degradation of the ST1 circuit. Meaning that again, you are only masking a problem, and it will reappear at some point as the system continues into entropy.

The second point I would like to make is that even if this situation is unique to you, and the best solution for you. People with similar problem will come and see that someone got their desired effect, and attempt the same solution. Ignoring proper troubleshooting, ignoring any attempt to solve the problem and not the symptom, and missing out on a good learning experience for proper maintenance of their car, that will benefit them and keep their car on the road longer with true repairs and not band aid fixes.
 

jdmfreak

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The thing that worries me here is that you have removed only one wear item from the circuit, the starter relay, which I would assume you have already tested so that wasn't the issue. The other two are the IGN switch and the starter contacts. Both of which could still be an issue. Like Pi said, you might only be masking the problem. It could very well come back. Also the factory starter relay only exists to give the clutch switch and theft deterrent computer easy disable control over the start circuit. The addition of a relay in a bypass circuit is pointless, ST1 was designed to carry both the inductive and switched loads of the start circuit. Unless it's to boost power to the system adding a relay to a bypass circuit merely adds failure points where there doesn't need to be any. And if the relay was added to boost power to the start circuit, then that indicates degradation of the ST1 circuit. Meaning that again, you are only masking a problem, and it will reappear at some point as the system continues into entropy.

The second point I would like to make is that even if this situation is unique to you, and the best solution for you. People with similar problem will come and see that someone got their desired effect, and attempt the same solution. Ignoring proper troubleshooting, ignoring any attempt to solve the problem and not the symptom, and missing out on a good learning experience for proper maintenance of their car, that will benefit them and keep their car on the road longer with true repairs and not band aid fixes.
Well said!
Not to mention the complete headache given to the next owner if you ever sell the vehicle...
I have Worked on a few old fords and chevys that whoever worked on them before fixed them by adding wires. Pita to diagnose a wiring issue especially when you get used to fixing stuff that way and end up rewiring/double wiring a bunch of circuits
 

CyFi6

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I can't figure out what all the fuss is about in this thread. Take the info provided and use it if you so please... You can hate the idea all you want, you don't have to use it nor is it your responsibility to make sure nobody else does, people can make that choice for themselves. Its a suggested resolution to a problem and nothing more. I think we can agree that this is not the way you should do a "proper fix", but in a lot of cases it works and for some people that's enough. There are pros and cons to both ways of resolving the issue.
 

jetjock

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Crack me up. It basically comes down to people rising to the level of their own incompetence when fixing stuff. It's something that seems to be a theme among MKIII owners.
 

Dan_Gyoba

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All the "hate" is about one thing. This is a problem that is more than easy enough to fix properly, rather than have this band-aid which may not even permanently resolve it.

I'm not against replacing wires, or relays, or whatever, so long as the problem is understood, and the solution is clear. For example, I ran a new piece of wire between the headlight relay and the #2 integration relay in order to get past an issue with my motor swap, which is that the factory wiring which runs there also goes to the ECU, which was grounding out the headlight relay, the result of which was that if the battery was connected, the headlights turned on. My fix was non-ideal, but I knew that I was fixing the problem when I did it, because I knew exactly what the issue was. Had I found more information, which I have subsequently found, I would have changed the pin in the ECU harness to the correct one for the headlight idle-up for the '87 ECU, which is different than the pin for the '89 ECU, but I did not have that information at the time.

I suppose that the issue is that people should know that this is a band-aid, and not a proper fix. If the problem is the ignition switch, it might fix it in the short term because the ignition switch still works enough to trigger a relay, but if the switch is wearing out, then it will continue to wear out, and eventually will not be strong enough to consistently manage that. The mod as posted also still uses the starter relay and/or neutral safety switch, which could also continue to deteriorate. As done by Satan, this would bypass an automatic's neutral safety switch or manual clutch switch, which could mean in-gear starting.

For "old wiring" this gives me real facepalm moments. There are so many critical wiring systems in the car, many of which have the potential to do real harm to you or your engine if they are not working correctly, whereas the most harm that the starter circuit not working correctly can do is inconvenience you. If you are so worried about the starter solenoid wiring that you're planning to replace it... What are you planning for the EFI system circuit? How about the ignitor circuit? Or the fuel pump? Or the fuel injectors? the AFM? How about other safety related systems? Even simple things like brake and signal lights can be a real safety hazard if they don't light up correctly. If you're concerned about the wiring and planning to replace it simply on the basis of age, then why aren't you ordering at least a new engine harness, if not both engine and chassis harness, complete with all new relays and switches? (Well, besides the fact that doing THAT right would cost more than almost any Mk3 is actually worth.)
 

Dirgle

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I can't figure out what all the fuss is about in this thread. Take the info provided and use it if you so please... You can hate the idea all you want, you don't have to use it nor is it your responsibility to make sure nobody else does, people can make that choice for themselves.
You know I really shouldn't be surprised that you would think this way, but somehow I still am.

If these changes were done in their own garage to their own car and that is where it stayed you'd be right. Whatever they want to do is their own business. The problem begins as this forum for discussion becomes a knowledge base where people come to research solutions to problems they are having. The power of the forums, both destructive and creative, comes form the ability for someone to post a solution to a problem and it to be constructively criticized for its technical solidity. If the knowledge pool of the forums is strong then the final solution becomes better. But as the quality of the knowledgepool degrades you begin to get a lot of inaccurate information and noise. And as more people come to use this inaccurate information it reinforces itself, and grows. So in the interest of purifying the knowledge pool, inaccurate information and poor practices need to be identified, isolated and corrected if possible. This is a natural and automatic function preformed by a community. That is why we keep pointing things out to Mr. Satan each time he comes back and says his solution works and it's great.


Its a suggested resolution to a problem and nothing more. I think we can agree that this is not the way you should do a "proper fix", but in a lot of cases it works and for some people that's enough. There are pros and cons to both ways of resolving the issue.
The big issue is that this isn't a solution to a problem. It is a solution to a symptom. And since the base problem has not been solved it stands to reason that it will return with more symptoms. With people who followed the guide, coming back later after having them fail again, and saying the MKIII's have weak/faulty electrical systems, when that is not the case at all. The MKIII has weak/faulty owners who can't be bothered to troubleshoot and repair a problem correctly. Also pros and cons of resolving an issue are irrelevant until you get past the first level of problem solving, right or wrong methods. Once you choose right or wrong, you move to the next level, the one most people seem to have the most trouble with, proper or half-assed.
 

Poodles

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I can't figure out what all the fuss is about in this thread. Take the info provided and use it if you so please... You can hate the idea all you want, you don't have to use it nor is it your responsibility to make sure nobody else does, people can make that choice for themselves. Its a suggested resolution to a problem and nothing more. I think we can agree that this is not the way you should do a "proper fix", but in a lot of cases it works and for some people that's enough. There are pros and cons to both ways of resolving the issue.
It's the electrical equivalent of fixing it with duct tape.
 

jdmfreak

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If you're good enough at reading a wiring diagram to do this "fix" then you're good enough to diagnose and repair it properly... Doesn't take a genius
 

Satan

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Still? Really?

I am very familiar with running new circuits for the signals still needed after my 2JZ swap. I have done several 1JZ/2JZ to MKIII wiring harnesses. The signals which are necessary remain and I am very aware of the "proper" way to fix, if you want to retain factory design/material. I know how to solder and heatshrink and do "proper" repairs. Although I skipped it, I also know how to test/diagnose the issue.

The challenge from other members about this "mod," was that it does piggy back on the existing circuit (and issues). The mod, while works effectively, is a temporary solution because the root cause remains undiagnosed/unresolved. So, as it's been said too-many-times, this is not a mod, but a temp-fix. Can we agree on this?

______________________

In my case, I have a known-good starter, known good ignition switch, with questionable (undiagnosed root cause) in between. I have a 160 amp alternator and have done the "Big 3" power wire "upgrades," as well as a few other goodies I added with my aftermarket alarm (which I also installed a few years back). The dash harness is auto and the neutral start was eliminated when I went with the R154/2JZ combo... common issue/feature with that swap (I purposely did not enable my remote start alarm-features). I am VERY familiar with the circuits and configuration in MY car.

Instead of piggybacking on the factory circuit, or counting on it further, I decided to replace it (keeping the signals which existed prior to this work). I am not sure what the fuss is about, other than I decided it was worthwhile to me to replace wire & components which have already given 20+ good years. I've done it professionally with quality material. It is not Mickey Moused. The same EXACT circuit exists now (as it did last week), with non-Toyota wire and Bosch relay. I've documented all of my work and can email to the next owner, if there ever is one (I plan to keep my MKIII forever). I'm sorry everyone seems to be still looking for root cause. If you have the issue and have read this thread, you know what to do to find it, if you want to.

The same argument exists about the fuel filter, by the way. Some say it's designed to be there forever, blah, blah, blah.. Something else that I replaced because I felt it had done its job and replaced "just because." I did not band-aid and have FULLY accepted that the remaining old-component is the ignition switch. I have also planned/prepared to re-address, if the problem pops up again (I am positive it will not tho).

EVERYONE should do their own homework and do the best that they can do or want to do under their specific circumstances. I felt like adding to this "mod" thread, so that it is another alternative to consider, if you already have the material, know-how, and want-to.

I can't believe all this ruckus is about something so simple.

Ninja edit: I did not recreate the NSW circuit for my 2JZ swap. As many of the MKIV guys and others do, I wanted to remove the clutch/NSW. I have had crank walk, and it SUKS. Also, it was VERY cost-effective not to order a new chassis harness (if available) for me to address this one issue. Even if the harness was cheaply/commonly available, I still may have done it this way, rather than remove/replace the harness (dash).


8/31: Mocked up the distribution block & the starter relay....
1234930_10200564003802066_724008410_n.jpg
 
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Agallington

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I have an 88 turbo. I already purchased the new engine harness and installed, but still getting the no start click when hot. Is this something that will eliminate this? My splice would basically be into my new harness. I have read this and understand others thoughts, just wondering if this would help, or should my ignition be replaced?
 

hvyman

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If you have a new harness the problem is the dash wiring or the ignition switch.

Or you could just do the relay mod.
 

hvyman

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It could also mean that there is low voltage to the starter.
 

Agallington

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Not saying it couldn't be the starter, but it is pretty new. It has no problem starting when the engine is cool or cooler. When this happens, my turbo timer, which displays battery voltage shows 10-11 amps only. Connected right after the ignition. It will a
Most always eventually start, but sometimes it takes a while. Could this be a starter relay problem even though it is only when warm(as far as I can tell so far), or ignition, or?...
 

IJ.

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Not saying it couldn't be the starter, but it is pretty new. It has no problem starting when the engine is cool or cooler. When this happens, my turbo timer, which displays battery voltage shows 10-11 amps only. Connected right after the ignition. It will a
Most always eventually start, but sometimes it takes a while. Could this be a starter relay problem even though it is only when warm(as far as I can tell so far), or ignition, or?...
Amps or Volts?
 

jetjock

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10-11 volts is the problem right there. Indicates either a discharged battery or a severe voltage drop. Again, as I've said several times in this thread, all of these problems can be easily solved by the proper use of a meter. Just do it. Don't know how? Now would be a good time to learn...
 

gsxr141

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i'm on my 3rd aftermarket starter in a year. this time i went with a bosh. same shit after 3 weeks though. i firmly believe it has something to do with the extreme underhood temps. the car will start 75% of the time, but when it doesn't there's no click or anything. if i tap the starter with something it fires right up.
i know that there's a common problem with the wiring in these cars, but tapping the starter = mechanical failure and not an electrical problem.
i'm going to try a starter heat shield or blanket as well as a turbo blanket.
 

Nick M

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but tapping the starter = mechanical failure and not an electrical problem.
As long as arcing didn't cause the brush to fuse in the rear position. Because that has never happened.
 

jetjock

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Correction by tapping indicates worn brushes and/or worn solenoid contacts, both of which can be replaced. And while they can be at fault for the problem talked about in this thread they seldom are.
 

gsxr141

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Correction by tapping indicates worn brushes and/or worn solenoid contacts, both of which can be replaced. And while they can be at fault for the problem talked about in this thread they seldom are.
i agree with you on that point. my question is WHY they are going bad so frequently. a attribute it to th excess heat under the hood. although i am open to any other ideas.
 

3p141592654

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Poor quality rebuild. I have a rebuilt starter from Toyota that has been trouble free for over 10 years now. The underhood temps of the Supra are no hotter than other newer cars I own, which is to say hot! Densely packed engine bays and catalytic converters = a toasty environment.
 

hvyman

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Aftermarket starters and alternators are complete junk now a days. Id buy 10 used before id put a aftermarket one on my car. Cant even count how many ive done under warrenty when i worked at a independent shop.
 

JDMMA70

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I wish I saved the pictures of my first aftermarket starter when I took it apart for the contact issue. Trash. You can however rebuild these with Toyota parts no problem though.
 

ZoomZoomZoom

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Aftermarket starters and alternators are complete junk now a days.
Amen! I went through the hit-the-starter-with-a-wrench phase too. New OEM starter was the solution.

I also went OEM with the alternator and master brake cylinder. Save yourself time and money and just replace those with OEM from the get-go.

Now I need to find a solution for the crappy rebuilt brake calipers..
 

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did the relay and it is now hacked.
ftfy

On the subject of the starter, 99% of the time it's the contacts in the starter and not the solenoid windings or motor. The rebuild parts are VERY cheap for this failure and it's extremely easy to do.

Failure isn't going to be heat related as it's on the wrong side of the motor for that to be the issue. Many cars run the starter right under the exhaust manifold (with a cat in it) and they don't have issues.

Disassembly, cleaning, polishing the communicator, and lubricating the bearings/bushes is all very simple (though this is rarely the issue but is good preventative maintenance while it's out). Then again I've been rebuilding motors since I was little...
 

gsxr141

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whatever is causing the problem, this fucking bosh starter i bought is worse than the cheap autozone one i had before. it almost left me stranded 3 times today. wtf!!!
 

Poodles

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whatever is causing the problem, this fucking bosh starter i bought is worse than the cheap autozone one i had before. it almost left me stranded 3 times today. wtf!!!
Does it simply click, or do you get nothing? If it's clicking and still not starting, it's possibly the contacts (later style contacts are longer and don't wear as fast). If it's not clicking at all, it could be the plunger was installed dry and it's sticking, or the relay/wiring is bad.

Simple search for "denso starter rebuild" in google has tons of info and places to buy the kits. This is what worn out contacts look like: