Weirdest Non-Starting Problem

[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.