alltrac

Today my 93 SC400 started acting up on me. I went for a short drive and returned. Went back out a few hours later and would not start. The starter spins fine. During the no start issue, the check engine light does NOT come on with the key in the "ON" position. The fact that the CEL is not illuminated when the key is in the "ON" position gives a good indication that the EFI MAIN relay is a good place to start looking.

I replaced the relay with one from my Land Cruiser. Still no start. Put original EFI MAIN relay back in, still no start. Land Cruiser starts fine with both relays. 2nd try, I turned the key to "ON" (still no CEL), pulled the EFI MAIN relay and put it back in. This time there was some servo sounds, a few relay clicks, CEL illuminated and car started.I was able to replicate the results easily 3 times.

So the EFI RELAY might not the cause but is involved with this issue. Other connected parts are the ECU, Circuit Open Relay, Ignition Switch, battery, and ground.

I think my first troubleshooting attempt will be to check for voltage at the +b and +b1 pins where the ECU receives voltage from the relay. Voltage at the pin and NO CEL will confirm the ECU. No Voltage at the pin and I'll start working backwards from the ECU.

Ryan
93 SC400
92 Land Cruiser