I have all relays, the harness is getting power feed, the computer is hooked up,and grounds are good, but the check engine light on my painless harness will not come on when ignition is on, the light will come on and go off when ignition is on,if it does not come on that means there is no power feed in harness, well I used a meter tester and it has power. anyone done a LT1/Iroc swap? any suggestions?

Also..... I disconnected the battery then computer,then put the battery back in and put the ignition on and used the meter on the harness connectors for the engine such as injectors,canister solenoid and other parts. Some connectors showed voltage and some didnt, remember I had the computer disconnected not knowing if I needed this for all connectors to get power. So if I disconnected the computer, and put a meter on the engine connectors while ignition is on, are all of these suppose to contain a hotwire in the conector that shows voltage?I tried about 3 injectors and none had voltage.

 

I have never enjoyed troubleshooting a Painless harness but here goes. The SES light should have ignition to the bulb and then the computer grounds the circuit. Make sure this is how that circuit is wired. Otherwise, the computer will not see the proper voltage on the SES circuit and will not know to turn the light on, and will set the SES circuit malf. code.

As far as the voltage test with the computer unhooked - the computer will feed a 5v signal to the appropriate sensors and normally grounds other circuits for their operation, i.e., the injectors are grounded by the drivers and the purge canister is grounded when the parameters are met by the tables. The injectors will all have ignition power (12v) with the key on, l regardless of the computer being plugged in. This will not change. Double check your ground on the tester and recheck the circuit. A good rule of thumb to remember on GM vehicles is pink is ign power and orange or red is bat power. Painless doesn't stray too far away from this but don't quote me.

 

All the circuits in my painless harnesses fuseblock has juice except for: The injectors circuits, and the Fuel Relay,MAF,and Vats Module circuit.

 

When you say:


Do you mean the light is on and when you turn the ignition on it goes off? Or does it just come on momentarily and then shut off?