I’m needing some help figuring out why my truck won’t start . No spark or fuel and no power to coil , asd relay and Hall effect replaced and can feel it click when ignition turned on . How can I check to see if the ECU is working or not ?

 

is the relay getting constant power? if the ecu is working it will usually shut spark/fuel not long after turning the key on.

 

I would say pcm is working if the asd relay clicks on since it's controlled by it. It doesn't stay engaged when the ignition is left in the on position. It will shut off the asd relay after a few seconds if the engine is not running. May want to test it again with a meter hooked up prior to turning the key. The asd relay powers the injectors, coil and fuel pump.

 

I’m going to check to see if the power is constant , good point , the ecu is suppose to shutdown the asd relay intermittently correct ?

 

Relay is getting constant power to 3 of the 4 contacts ,red , blue and yellow and blue and white

 

is the check engine light still coming on before you try to start it?

 

I’ve never had the check engine light work or come on in my truck the 9 years I’ve owned it or would’ve been checking for codes . I’ve been meaning to pull the cluster out and check the bulbs , is this worth looking at first ? Yesterday I used a light tester across the fusible links and found power across each side . I have bought a new ecu but am trying to find root cause first before I install it

 

usually it comes on before you start the engine. it would also help tell if the ecu is bad or not. with how old these things are it is possible the ecu went bad and nothing caused it other than it just being old.

 

It was the computer , I also replaced the bulbs in the message center , check engine light works now when I turn the key on . I did the key dance and got codes 12 and 55 If I counted them correctly

 

Normal. If it starts and runs good, run with it.