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Jake
Jake, Nissan Technician
Category: Nissan
Satisfied Customers: 3788
Experience:  Experienced collision repair technician, Pulaski Tech graduate and DSM hobbyist.
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2001 nissan pathfinder 3.5 ecm relay will not power up

Customer Question

2001 nissan pathfinder 3.5 ecm relay will not power up
Submitted: 5 months ago.
Category: Nissan
Customer: replied 5 months ago.
the relay is a 6 pin 2 w/r have power 1 r/w has power l/b has power b/w and r will not power but will power for a second if batt been unhooked then hooked back up
Expert:  Jake replied 5 months ago.

Hey there, thanks for the question.

can you tell me a little bit about what's going on that led you to the ECM relay in the first place please?

Customer: replied 5 months ago.
unit would not start had ecm replaced then got to checking and found relay concern now i can start unit if i power up red wire from relay which appears to go to injecters and idle speed motor
Expert:  Jake replied 5 months ago.

The injectors do not receive power from the ECM relay. they are fused directly. They receive a ground from the ECM itself which does receive power through the ECM relay. The coils also recieve there power through the ECM relay.

Expert:  Jake replied 5 months ago.

if the white/red and the red/whites have power then your fuses are fine.

Expert:  Jake replied 5 months ago.

your problem is the coil side of the ECM is not being grounded by the ECM and not closing the relay switches or the relay itself is bad.

Expert:  Jake replied 5 months ago.

The only likely reasons that the ECM would not ground the coil side are as follows. The likelyness of them being the culprit is in the order they are listed.

1. Camshaft position sensor

2. timing off / timing belt broken

3. crank sensors.

Expert:  Jake replied 5 months ago.

If you need further assistance just ask and I will be happy to help, if not please just be sure to leave a kind rating.

thanks.

Customer: replied 5 months ago.
how do the cam or crank sensors making ecm ground where it looks to me b/w white wires power supply when ign is on
Expert:  Jake replied 5 months ago.

Because if the ECM cannot determine engine position (timing) then it will release the ground from the ECM relay to cut spark and protect the engine from damage.

Customer: replied 5 months ago.
which wire is ground
Expert:  Jake replied 5 months ago.

on the ECM relay?

Expert:  Jake replied 5 months ago.

the blue/black wire that runs from the ECm to the coil side of the ECM relay switches it on and off. The ECM uses a ground signal to do so.

Customer: replied 5 months ago.
i guess i will try cam sensors both crank sensers have been replaced ????
Expert:  Jake replied 5 months ago.

If you know the mechanical timing is good then yes. Did you check the timing when replacing the bottom crank sensor?

Customer: replied 5 months ago.
checked timing through scanner does not have a dist coil on plug
Expert:  Jake replied 5 months ago.

yes, I am referring to MECHANICAL timing not ignition timing.

Expert:  Jake replied 5 months ago.

what does the intake timing look like on the scanner when cranking the engine?