groundzer0

97 sc300. have the speedo problem everyone has it seems...i put a new speed sensor thinking that was the problem but it didnt do anything. im trying to get this thing inspected but cant get the ready codes to set because the ecm doesnt see speed. looking at this wiring diagram i have it shows blue/red wire going from vss to plug d13 on speedo as vss input, and comes out orange wire plug c2 as vss output to engine harness (left side of engine) to pink wire to ecm (doesnt say which plug on ecm. if this diagram is correct i should be able to wire it straight to the ecm for it to see the signal, unless it converts the signal inside the speedo and ouputs that to the ecm. for some reason i cant find an ecm pinout diagram for 97. any input is greatly appreciated this thing is seriously getting on my nerves!!!!

i know there are other vss wires on the ecm but i dont know where or what they do, ive just seen writeups for navi systems. the one on this diagram says sp1 so im guessing thats input

groundzer0

also weird thing now too, the speedo was working intermittently with the odo working at the same time. now the speedo hasnt worked at all in 2 days but the odo works for a while after startup....

chowda

Hi GroundZero

I actually am having a speedo issue too. While I have an SC400, I wonder if my problem is similar to yours.

I have started another thread on my speedo issue...It stopped working after I swapped in an 93 sc300 manual trans.

I have already checked 12v to the plug and the ground from the plug is good. There is also a voltage from the return so the sensor is good (Have you checked these?)

Anyway I know the cluster isn't getting or sending a signal a signal to the ecu because I have overboosted steering at high speed from the car thinking that it's stopped (power steering ecu).

I'm wondering if our issues are related in some way? Not sure but I'll keep you posted on what I find.

Thanks,

Marvin

TaninAuto

There is only VSS signal going into the cluster. If the odometer works and the MPH needle does not work then there is a problem with the MPH needle motor or main board.

If neither work then there is no signal going to the cluster.