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my 1997 Lexus ls400 is still in at the mechanics, with a so far undiagnosed electrical problem. We thought it may be the immobilizer but something else came up and it might point to the problem.
the OBDII wont connect. we have tried to connect a generic OBDII scanner and a toyota techstream computer to the car and nothing. what would prevent this from getting any connection?
upon some inspections we noticed that the radiator fan is running consistently and to prevent the battery from discharging we pulled the main engine breaker and found some scaring ive included some pics.
does anybody out there know if the immobilizer is activated or not functional does that shut off the OBDII connection of are these two separate issues?
When the voltage ripple at the ECU's Vcc line exceeds the limit, these problems often occur.
● problems in getting into diagnostic mode or scanner says "no communication"
● OBDII port is unresponsive, seems dead
● ECU not communicating with scanners or not displaying codes with jumper installed
You can find more at the FAQ. Electrical:
Sorry, I should have mentioned that the ECU is good. It has been sent in to be tested twice and passed all simulator tests, and I purchased a second used one (same number) just to triple check that the ECU was ok, that was our first point of failure and we can safely rule out the ECU as the problem
Hmm it does sound like youve done everything to rule out the ecu. The marks around the contact point of the relay doesnt concern me much, both of my LS's have that. I believe it is from the 20 year old contact grease put on from the factory, not from burning. Although heat definitely played a part. To clarify, youre saying the AC fan is always running? Like as soon as the key is in the ON position?
No, the radiator fan is coming on, the car doesn't start, only cranks, so the engine is cold and the radiator fan should not come on when you turn the key to on position
if the engine was hot or above a certain temp then the radiator fan should turn on. It should not be on all the time just when you turn the key to on position,
The car has been at the repair shop for almost 2 months now and the new battery was dead, We started pulling breakers to turn it off and the one that got the fan to turn off was the main breaker shown in the pics above
97 LS 400 just bought. Perfect car except while on the lot someone stole the radio and the handy man/ mech rewired and added a used aftermarket radio and now when volume is turned up the radio goes out for a sec and the AC goes warm. Air went warm again when someone used the power seat on pass side. Once you turn off and turn on AC blows cold again. No fuses blow just resets itself any idea where to start?
Some of those wires are going to need to be traced back and connected properly. That may also resolve the 1.7V to the igniter issue.
That problem ended up being the AC clutch and/or the AC relay on the main fuse box. when these were replaced the problem resolved itself, AC has been fine for well over a year. The currently non starting is related to the immobilizer, as both the voltage to the coil and fuel are cut off which is exactly what the immobilizer does. We are thinking of getting a used engine fuse box and just replacing the whole thing fairly inexpensive and easy to change out. Im still trying to get information on the OBD and if that is related to the immobilizer or a separate issue. Does anyone know if the OBD is disconnected/cutoff if the immobilizer / security system is activated?
I have to admit I didn't consider the aftermarket radio as the source of the issues. pulling the fuse and or isolating it should be an easy thing
OBDII conection not working
