In the process of chasing a speedo, c.c., od problem

Tried to ground overdrive solenoid but didn't work

Tested for 12volts on "blue" wire at overdrive solenoid and got nothing with key on tried all shifter position

Got continuity through it to pcm plug with battery disconnected but no 12V


Anyone

 

What year? go to quick links and edit signature to fill out.

 

sorry still pretty fresh on here

1992 w250 auto

 

That blue wire gets its power from the ignition switch. It power multiple things. A/c cycling switch, fuel heater, Fuel shot off solenoid. There is a black plug and a grey plug at the back of the cyl head kind of above the lift pump. That blue wire is in the black plug. 1 of the corner wires, its a rectangle plug. Check to see if power is at both sides of that plug. Check continuity to the pcm only checks the ground side. The pcm grounds the solenoid for OD. The orange and light green wire for the ground goes through the grey plug to the pcm.

 

ok so i checked the black plug at Tron suggested

12.06v on either side but no power at solenoid plug what now?

So the power wire doesn't hook to the pcm at all?

i can find continuity through the solenoid plug and the pcm plug

Could any of this come from a bad or misprogrammed pcm (mine was just replaced with a reman. due to charging issues)

 

You should have power to the blue wire in the OD solenoid plug when the key is on.

The PCM does not have anything to do with the power to the OD solenoid, it just supplies ground.