by wttmf on Mon, 01 Sep 2014 10:06 +0000
Further update.
ECU relay is in fuse box in a unit called "integration relay", it has 4 relays is one unit, ECU, EDU, fog, and horn relays.
I removed stripped and cleaned contacts and used some crc switch cleaner. After cleaning it would fire up each time every time, even my horn started going, it had stopped working a while back.
So i thought I had it, test drove close to home, did around 100k or so, lots of stop and starts, used it around the farm on/off on/off etc and all good.
Decided to do a trip to visit some mates 300k or so away, trip there was all good but on way home it cut out while driving (first time, before it just wouldn't start). This time engine light is on, but no start, usually it had no engine light when it wouldn't start.
So I pulled relay out and apart cleaned again and bag, fired up, drove home and still going.
Relay is $345 from toymota, and they said they are rare to fail and 2 weeks away.
I finally have a wiring diagram now and I see that the power from ignition goes to ECU then power from terminal MREL on ecu goes to power ecu relay and then power from relay goes back to ECU, seems a bit backward, usually ign powers ecu relay then relay to ecu.
I will have to wait to see if it fails again to test power to relay from ecu and power to ecu from ign switch, if power is not coming out from ecu to relay it could be a ecu fault BUT because every time i clean the relay it goes I'm thinking the relay is the fault. UNLESS the voltage to relay from ecu is low and cleaning just reduced resistance and allows relay to work on low voltage.. but will have to wait and see.