Weirdest Non-Starting Problem

[GCPRO]

I could not find this problem reported in another thread. It has been plaguing me for years now. Any ideas would be appreciated.

Problem:

• Car randomly will not start

Vehicle info

• 1990 Supra with 7MGE JDM engine replacement 3 yr ago
• T-top
• Viper alarm

Symptoms

• Not related to humidity, temp, engine temp, etc.
• Flicking key repeatedly sometimes gets it to proceed
• Leaving car unlocked seems to make a difference
• Not using Viper (use old style key in door to lock/unlock) seems to improve things

What’s been tried

• Replaced starter motor 2 times over last couple of years. Another one (Bosch this time) is going in this weekend (not expecting it to make a difference)
• Replaced battery
• Battery power and ground cables replaced
• Ignition switch and tumbler replaced
• Replaced relay supplying V to starter solenoid

My intuition is that the Toyota theft deterrent system is disallowing it to start, although I am not sure how to test/fix this. I got frustrated trying to follow the aftermarket Viper wiring installation and gave up.



Anyone else see such weirdness? Any ideas?

[SupraMan1784]

before i read that last sentence i was gonna say its teh factory security system...there should be a thread either here in general questions or the mk3 thread that talks about this a little more, if you replaced the ignition and all the components...i definitely would assume its the ant-theft system it gave me problems at the start but now its behaving so im not goin nuts like i used to

[toyota_guru]

Originally Posted by GCPRO

I could not find this problem reported in another thread. It has been plaguing me for years now. Any ideas would be appreciated.

Problem:

• Car randomly will not start

Vehicle info

• 1990 Supra with 7MGE JDM engine replacement 3 yr ago
• T-top
• Viper alarm

Symptoms

• Not related to humidity, temp, engine temp, etc.
• Flicking key repeatedly sometimes gets it to proceed
• Leaving car unlocked seems to make a difference
• Not using Viper (use old style key in door to lock/unlock) seems to improve things

What’s been tried

• Replaced starter motor 2 times over last couple of years. Another one (Bosch this time) is going in this weekend (not expecting it to make a difference)
• Replaced battery
• Battery power and ground cables replaced
• Ignition switch and tumbler replaced
• Replaced relay supplying V to starter solenoid

My intuition is that the Toyota theft deterrent system is disallowing it to start, although I am not sure how to test/fix this. I got frustrated trying to follow the aftermarket Viper wiring installation and gave up.



Anyone else see such weirdness? Any ideas?

check out behind the fuse panel under the dash, supras have a tendancy to leak at the door causing the back of the panel to corode and mess up the factory theft system. I've replaced 3 fuse blocks for symptoms you have described here.

[crusader1545]

also the viper alarm could do it it did the same thing to my dodge

[scruffboy]

It probably is the factory anti-theft system. This happened to me and I posted before about it. To re-set the alarm, turn the key twice to the left (with the door open). That worked for me for a while, then one time it didn't work. I remembered someone posted that the drivers side lock is always used and sometimes wears out the system, so to try the passenger side door. I did this and it worked. (See how it pays to read these boards) Does anyone out there know how to disarm this damn thing? It's way more trouble than its worth, and I would just as soon do away with the anti-theft system altogether.

Thanks,

James

[SupraMan1784]

im thinking about pulling the whole thing out and replacing it with a newer system...but i probably wont do it unless it starts acting up on me again... so far its been good no problems for a long while...hopefully it stays like this

[GCPRO]

So, this past weekend I replaced the starter motor with a different brand - Bosch. So far the beast is working great. The symptoms support a "limp" starter in that repeated key clicking would eventually get it to turn over. Also, it seemed to be more likely not to start when the engine was hot and then sat for a few minutes (increasing cylinder gas pressure).

I had ignored this possibility because I had replaced the starter before a couple times with no apparent long term fix (as I recall now, it did work OK for a month after replacement). But, being a cheap SOB, I replaced the starter with the same cheapest model from the same supplier. The Bosch certainly has more torque.

Consider this one closed unless (until) I return with the bad news. Thanks for the input.