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

[radiod]

Go back 4 posts (#137), read, think, decide.

It's a bandaid. It will only work as long as your half broken/bad connection stays half broken/bad and doesn't get fully broken.

 

[Woody1989]

Would this relay mod potentially work in my MKIII with an Aristo 2JZGTE swap? I had the same issues, click click click...start. I looked at the wiring in my car and it didn't seem to line up with some of the diagrams that have been posted in this thread. Any input would help.

Thanks.

Ben

My 2JZGTE swap is largely completed. Car runs and drives well, but not running any boost from the Turbonetics GTK-850 yet. Base map tune on the EMS-6860 from DriftMotion. My guy (George) that did the swap said he found the "bandaid" relay fix on the old 7MGTE and removed it. He traced the problem back to the passenger kickpanel relay that was only getting 6VDC rather than the 12VDC it needed. He said the wire in the harness feeding the kickpanel relay was possibly bad etc? He just bypassed it and so far I haven't seen any problems. Only had the car back now for a couple days though.

Best,

Brad

 

[JD-MK3]

About a year ago my car started with the random starting. Installed the 30 amp relay and started the first time every time. Still haven't read about ANYONE finding and fixing the ACTUAL problem. Just a bunch of ego maniacs blowing smoke. BTW, the stock spade clip connector was totally burned up from arcing.
-Joe

 

[Poodles]

About a year ago my car started with the random starting. Installed the 30 amp relay and started the first time every time. Still haven't read about ANYONE finding and fixing the ACTUAL problem. Just a bunch of ego maniacs blowing smoke. BTW, the stock spade clip connector was totally burned up from arcing.
-Joe

Then you obviously didn't read this thread...

 

[machcnz]

FYI - Both The Soarer UZZ3#/JZZ3# (Lexus SC400/SC300) and JZA80 utilise a 'Starter Relay' located in engine Bay, perhaps to reduce cable resistance and in cabin starter cable wire gauge.
My JZA70 has the symptoms identified in this tread, and the apparent cause is start Wire resistance when hot. I plan to identify the root cause, but I suspect in identifying and locating the root cause, adding a relay in the engine bay - once fixed - may well be a worthy modification by reducing current flow over this rather long circuit.

Will let you all know my findings.

- Marc 91 JZA70-R

 

[machcnz]

Update - Measuring circuit resistance from battery post to Start Signal wire was 0.2 Ohm. Measured by applying a Lamp and loading over this circuit determined a 1.35 ohm drop across the signal wire circuit. So in my case, the start-signal circuit does not appear to be an issue. Inspecting battery post terminals appeared revealed some corrosion and were thoroughly cleaned, perhaps the more likely culprit.

So far, no starting issues, but will reserve judgement until proven.

----UPDATE 18/1/2012----
No starting issues over 1500KM.

----Update 01/03/2012
No starting issues since Nov/2011

 

[ifyouaint1sturlast]

Bringing this back to life.

I've been having this problem recently. I've tested and found that at B1 I'm getting 12v on ACC, 12v on ON, and 7v on START.

I will do more testing and get back.. but, has anyone experienced this? Less voltage from the ignition cyl? Doesn't it all come from the same wire? AM1..

Would this indicate it's an issue inside the cyl itself if there is 12v going in, and 7v coming out.. but only on one circuit?

 

[Poodles]

I assume by B1 you mean the postive lead of the clutch safety switch? Shouldn't have voltage unless it's in the start position, but it's also used for the cruise control...

 

[3p141592654]

Put your voltmeter across terminals 1 and 4 of the IGN switch and measure the voltage during cranking. Should be <1 V if all is well with the switch.

 

[ifyouaint1sturlast]

I assume by B1 you mean the postive lead of the clutch safety switch? Shouldn't have voltage unless it's in the start position, but it's also used for the cruise control...

B1 is the body plug under the dash that feeds the engine harness many signals.

Put your voltmeter across terminals 1 and 4 of the IGN switch and measure the voltage during cranking. Should be <1 V if all is well with the switch.

Will do today, thanks.

 

[3p141592654]

I assumed the 7V was measured during cranking on pin 12 of B1. Is that correct?

Yes, it all comes from AM1, except for the ignition circuit which is AM2.

You will also want to measure the voltage drop across pins 2 and 4 of the starter relay in the pass kick panel. Should also be <1 V during cranking. That should isolate your problem. Since the relay pins are tough to access, I would suggest measuring at B1 pin 12 and IGN sw pin 1, or you can go from the driver kick panel, whatever you think is easier.

 

[ifyouaint1sturlast]

I assumed the 7V was measured during cranking on pin 12 of B1. Is that correct?

Yes, it all comes from AM1, except for the ignition circuit which is AM2.

You will also want to measure the voltage drop across pins 2 and 4 of the starter relay in the pass kick panel. Should also be <1 V during cranking. That should isolate your problem. Since the relay pins are tough to access, I would suggest measuring at B1 pin 12 and IGN sw pin 1, or you can go from the driver kick panel, whatever you think is easier.

You are correct!

Pin 2 of the relay is IGSW-1 and Pin 4 of the realy is B1-12?

Thanks!

 

[mk3tattoos]

Now I'm having this issue&#128542; great!!!

 

[Satan]

Just did this after changing the starter... def something to be done 1st. I even re-ran the wire to the starter, all the way from the B1 connector. Issue seems to be in the dash wiring to the starter relay. Starter turns when its supposed to now.

 

[mk3tattoos]

Getting ready to start wiring things up, but I'm thinking about the full bypass altogether since there are some Supra's out there that came from the factory like that&#128513;.

Has anyone else done the canadian mod too? Or ran a new wire, really wanna know how that was done exactly. Thanks!!!!!

 

[bxiong17]

I am trying to do this mod to my 90 supra 7mgte, but can't find that ignition wire.. where is that located? and what color for this model?

 

[Poodles]

Try reading the thread. Long story short, it doesn't fix the issue at all.

 

[nrdriver]

I am currently having this issue. since the beginning ive believed it has been the antitheft computer. as many people have said here. its not hard to diagnose the starter circuit, you can do this mod as a fast way to tell that your ignition switch and starter arent bad.

ive been a technician for 13 years and very few times have i seen "just bad wiring". its not an inherant problem. but i do believe that the supra does have a common problem with the starter circuit.

this being said i believe the common problem is a bad ground. you can have an intermittent bad ground because the anti theft provides the ground to the relay. so tomorrow im gonna ground the relay to the chassis. if this fixes it which i believe it will and probably will with alot of our cars. Its an anti theft circuit problem which has a ton of components i dont care to test and spend the money to replace cuz i dont use it.

this is a step better than making your own circuit to replace a relay that i dont believe is bad.

feel free to give me your input and please dont judge me on grammar and crap as i am typing this with a 5 month old crying in my other arm lol

 

[Maple191]

I am currently having this issue. since the beginning ive believed it has been the antitheft computer. as many people have said here. its not hard to diagnose the starter circuit, you can do this mod as a fast way to tell that your ignition switch and starter arent bad.

ive been a technician for 13 years and very few times have i seen "just bad wiring". its not an inherant problem. but i do believe that the supra does have a common problem with the starter circuit.

this being said i believe the common problem is a bad ground. you can have an intermittent bad ground because the anti theft provides the ground to the relay. so tomorrow im gonna ground the relay to the chassis. if this fixes it which i believe it will and probably will with alot of our cars. Its an anti theft circuit problem which has a ton of components i dont care to test and spend the money to replace cuz i dont use it.

this is a step better than making your own circuit to replace a relay that i dont believe is bad.

feel free to give me your input and please dont judge me on grammar and crap as i am typing this with a 5 month old crying in my other arm lol

I personaly agree with you about the ground issue. As even the canadian spec moddles have the problem. However we use a different ground point.

But Ive also noticied that if try to start the car with cirtain acceseories on it wont.


Also my other opinion is that it has to do with the actual ignition switch possible being corroded and acting as a load on the starter circuit.

 

[jetjock]

Again, pinpointing the exact location of the resistance on any particular vehicle isn't difficult. Just takes using the right technique. One that, for best troubleshooting, *requires* a load on the starting circuit.

Grounding has never been the cause on the cars I've fixed. Not that it's impossible but it doesn't make much sense it would be grounding. That especially applies to the theft box grounding the inhibiting relay since that ground isn't required for the starter circuit to function. Not does the inhibiting circuit carry the starter trigger current. And as pointed out Canuck cars don't have the inhibit, use a different ground point, and yet still suffer the problem.