Starting problem, please help !!

[lewis87mk3]

Alright, I finally got my supra all back together again and now I have a problem.
I turn the key to on position, everything is normal, dash lights come on etc.. headlights work, bright, everything works.. but switch to start position and car does not crank, the starter solenoid does not even click. Battery fresh and charged from my other car. Both terminals replaced and refreshed.

So, my first thoughts, clutch pedal start switch, I tried bypassing it, didnt matter, still no start.

Then security system, i tried bypassing it, still no start.

Then clutch starter relay on passenger kickpanel, tried replacing, still doesnt start.

Still not even a click from starter solenoid. The only thing that is noticable when the car is set to start position is the digital clock dims, as it should, telling me that my ignition switch is probably still good.

Also this is a 1987 toyota supra turbo manual, never switched over from automatic so its not a harness issue, and the thing ran perfect with my old engine till rodnock. So I cant imagine what this problem could be?

Then I try (with the car in off position) running a wire directly from positive battery terminal to the solenoid lead on the starter and bam, the thing cranks over.. indicating no problems with the starter or the solenoid.

Where the hell is my problem? Is there something I am missing?
Is there a way if worse comes to worse that I can run a manual pushbutton start bypassing all the garbage and start it directly from the battery, and still have my car function normally?

Are there mice living in my dash chewing shit up since its been sitting almost a year? If so, where should I be examining wires?

Please help, any info is appreciated

 

[MDCmotorsports]

Signal wire off the back of the starter......

Try there first.

 

[IHI-RHC7]

Hmm, when you say bypassing the theft system, how did you do that?
Did you short terminal 5 to terminal 13 on the theft computer connector?

 

[lewis87mk3]

Signal wire off the back of the starter......

Try there first.

Well I mean thats what I tried manually jumping to positive battery terminal, and when I did that the car cranked over.

I also used a test light on the wire end and it never gave power.

 

[IHI-RHC7]

Here's a schematic of the circuit.

Note that Pin 13 of the theft comp grounds the starter relay, and the power comes from the clutch switch.

 

[lewis87mk3]

Hmm, when you say bypassing the theft system, how did you do that?
Did you short terminal 5 to terminal 13 on the theft computer connector?

No, what I had found from one of my previous cars is that there is a little computer box under the dash right next to steering column named theft warning. When you disconnect the harness from that it disables the theft system altogether as if your car did not come equipped with one. I have done that with like 3 different supras and it worked efficiently, but if I am wrong and that didnt really completely disable it, then let me know.

 

[lewis87mk3]

Here's a schematic of the circuit.

Note that Pin 13 of the theft comp grounds the starter relay, and the power comes from the clutch switch.

That schematic does appear to help...
Am I wrong or does it look like I could try jumping pins 2 and 4 on the starter relay and see if my car would start?

 

[IHI-RHC7]

That schematic does appear to help...
Am I wrong or does it look like I could try jumping pins 2 and 4 on the starter relay and see if my car would start?

That would only work with the clutch depressed and the key switched to start.
That said, just because the ignition switch kills aux power when trying to crank doesn't mean that the switch is good.
The reason things dim is because the internals of the switch remove power from all outgoing circuits except the actuall signal wire that goes to the clutch switch. That is, even if the clutch switch doesn't become energized, the other circuits will still lose power.
Removing the theft computer from a supra completely disables the starter as the diagram above shows. The theft computer provides a ground to the starter relay at pin 3.
The most easy way to bypass the theft computer is to jumper pins 5 and 13 on the connector from the theft computer, this bridges the 3 terminal on the starter relay to the hard ground for the theft computer. Without grounding the starter relay, the car will not start.
If the theft computer is sufficiently bypassed, the starter relay should click when the key is turned to "start"
If the starter relay clicks with the theft computer plugged in, the problem is in the wiring from the relay to the starter, and as shown above, there is only one harness to harness connector between the relay and the starter itself.
More than likely, the problem was the theft computer and bypassing it will work, but on occasion, the ignition switches go out, and they can be fixed by disassembling the switch and cleaning the internal contacts. This procedure is not difficult in itself, but make sure you disassemble it in a place where the spings and balls in side cannot bounce out and get lost.
Good luck

 

[lewis87mk3]

Actually I think your right, I checked my other old supra and I did have the theft computer still plugged in. It was a previous year one, I think what I typically do is replace the 89 and up theft computer with earlier years so its not as much of a pain in the butt. My 92 alarm system was ridiculous, it could have been aftermarket too I dont know. Ill have to try jumping those connections and see what happens, thx.

 

[lewis87mk3]

It most definitely was the security system. I tried locking it and then unlocking it from the passenger side and it properly disabled and let me start the car... woohoo...
For some reason my driverside wasnt disabling it.
So I didnt have to bypass anything actually..
sweetness...

 

[IHI-RHC7]

Yep, the drivers door lock gets most of the use, and the switch goes out in that cyl long before the passenger side does.
Glad you got her going!