Help! SC400 wont crank. Alarm problem??

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oliver400

New Member
:rant: I first noticed this problem about 3 days ago, as I attempted to start the car I cycled the key to the start position and nothing. The dash lit up, the steering wheel tilted, etc just like always, everything seemed normal, but no crank. After a second attempt the car cranked and started fine. I thought nothing of it.

Upon consecutive starting attemps throughout the day and the next, the no crank seemed to get worse. Sometimes taking three or four attempts to finally get it to turn over.

This morning the car would not crank over at all, tried many times and nothing. Whatever was going bad is now dead.

My first step to troubleshoot was check battery voltage+ 12.8V full charge, no problem there. I then located the starter relay (black relay labeled "S" in the power distribution center under hood, left side) and force jumped the relay. the car cranked and started. I swaped the relay with an identical one from a different curcuit and the same problem. So obviously the starter and relay are fine.

I started thinking ignition switch, but the car is recognizing the key when I insert it (by adjusting the steering wheel), lighting up the gauges in run position (as usuall) and turning the lights off in crank (like it's supposed to) Which leads me to belive that it is sending the crank signal.

I also suspected the neutral safety switch as a possible cause, but the switch illuminates the correct shifter position on the cluster, and will not dim the light on crank attempt unless shifted to P or N, indicating to me that it knows whats going on.

That leads me to the alarm, which I dont know how to test. I dont imagine that re-setting it would help, seeing as how this was a progressive failure and not an instant failure. However I am open to any suggestions.

Any help would be greatly appreciated. I'm sure I can wire the ign. switch directly to the relay, bypass the alarm and be fine. But I'd rather fix it "right". Any tips on positively diagnosing the alarm module? Am I missing something?

Car is a 1993 SC400 U.S. 150K miles. All avail. options.


Thanks
 
Starter contacts

You might try starter contacts,
Kinda sounds like the same problem i had on my old land cruiser
(1993)
Did exactly what your describing
 


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