P0773, TCC solenoid blowing 20 amp fuse (1 Viewer)

Joined
Apr 9, 2002
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1,027
Location
Olympia, WA
I just picked up a '95 FZJ80. It is setting a P0773, Lock-up/SL solenoid circuit. I checked out the solenoid and it has proper resistance (11-15 ohms), so it said to replace the ECM. I thought maybe the driver on the ECM was maybe going bad and couldn't power the solenoid, so I wired a relay in place, the signal from the ECM triggering the solenoid and 12v tapped from the fuse block, going to the solenoid. I'm glad I fused it, as it has blown a 15 amp and a 20 amp fuse. The relay clicks when the solenoid should be engaged so the ECM is doing it's job.

I don't know why the solenoid would draw this much power. I have a wire back-probed into the trans harness so I can check voltage and I decided to check the resistance again. With the headlights on it is 30 ohms, driving lights, 20 ohms and door open, dome light on 17 ohms. If I close the door and have no extra loads, I get the appropriate 15 ohms. Why would the resistance of a solenoid in the transmission change with the lights? Maybe I need an extra ground to the transmission?

A side note, I thought of some interesting uses for the relay controlled TCC solenoid, as long as you don't forget to turn it off.
 
Joined
Apr 9, 2002
Messages
1,027
Location
Olympia, WA
Installed a circuit breaker in place of the fuse, and has worked fine. It tripped the breaker once, but hasn't since then. Still going to try and add another ground right to the transmission, or check existing grounds.
 

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