No volt reference out of pin 21 on ecm. 3 ecms installed.Grounds at engine at aldl and alternator repaired. Wiring all checks out good.
Any idea's
Gary

 

What is your application here? Motor? ECM #?

 

ECM. Put 3 in car . No Votage from reference pin 21/416 circuit. No codes, check engine light on. Lamp driver good.
What in the car could cause the ecm not to put out a 5 volt reference at pin 21.
Grounds all repaired and good, wiring repaired and good.

 

With no +5 volt ref on that pin should get at least a TPS low malfunction code.

Remove the terminal from the ECM harness connector. With the ECM plugged in and key-on, engine off, check the voltage at the ECM pin 21. If it is now there then there is a short on that wire/device someplace.

If still no voltage check the BAT+ and IGN+ feeds to the ECM. They both require +12 volts for the ECM to power up and run.

Does the SES light turn on (key-on, engine-off)? If not, then either the lamp driver is bad or the ECM isn't powering up.

Does the MSC click at key-on, engine-off? Most likely it should (most ECMs do oscillate it, some do not). If not that is a sign that the ECM isn't powering up.

RBob.

 

SES light on all the time, driver new, if we ground it to the car light goes out.
No codes, mechanic cut wire 6 inches up pin 21 to take sesors out of play. No ref voltage. Will have him check bat voltage.
thanks