testing ecm

[tyfoo]

how do you test the ecm?
my typhoon is going back to the rough idle and promblems I had lasts summer
it seems that when it's hot out it runs like crap.

1- can't retreve codes untill I disconnect the relay for the i/c pump
2-code 22-tps
3-a/c not kicking on

 

[Divergent Lightning]

Re: testing ecm

The only way to know if it is bad is to replace it. I had the same dilemma myself.

 

[Crimson93Ty]

Re: testing ecm

Seems I saw something about that. The ecm has quad drivers in it (each driver is in a set of 4). So if one component has an issue, it will cause a problem for the other 3 being operated by the ecm of the "quad driving" set if I understand it correctly. If something that the ecm drives (relay for example) is bad, it isn't supposed to hurt the ecm but that driver will temporarily go out. Maybe the relay for the IC pump is grounded incorrectly or shorted to 12 volts and is causing an issue for the ecm. If everything acts correctly when that relay is disconnected, that would be my guess. I'm guessing at how the quad driver works based on what I've read. There are guys on here that know the ecm inside and out. Here it is:

A shorted solenoid, relay coil, or harness in a GMP4 computer will not damage the ecm, but will cause the circuit and controlled component to be inoperative. When the circuit fault is not present or has been repaired, the "quad-driver" will again operate in a normal manner due to its fault protected desgin. If a fault has been repaired in a circuit controlled by a "quad-driver," the original ecm should be reinstalled and the circuit checked for proper operation. ECM replacement will not be necessary if the repaired circuit or component now operatres correctly.

A/C won't kick on if freon is low due to the pressure switch on the side of the dryer (big aluminum can dohickey next to the intercooler). If the freon is low and the switch inside the truck is ON, you can take a paperclip and jump the connectors going to the switch. If you see the compressor kick in, you know everything else is ok and you need to have the freon level checked.