Mass Air Flow (1 Viewer)

[dglenn]

Ok, after a month out of state, I returned to repair a no start issue on my 94LC. Turns out that I had overlooked a 15Amp EFI fuse when running through all the ign diagnostics per manual. Not sure how EFI and no spark relate but in addition I have a code "24" on a diagnostic. CEL on. The truck is running but a little rough, my local mechanic says I need to replace the Mass Air Flow assembly. Can someone confirm code "24" Mass Air Flow? Could that have caused the EFI fuse to get fried or do I need to dig deeper? I did a full Head Gasket repair recently as well as oil cooler so I was all over the engine. Should I be looking somewhere else?

thx.

 

[jonheld]

Not sure how EFI and no spark relate

That fuse powers the engine management computer (ECU). Without that you get nothin'

 

[dglenn]

Got it, is it necessary to try and chase the root cause of that fuse failure, does it have any relationship to the Mass Air flow unit? thx.

 

[80t0ylc]

According to the '94 FSM, 24 CEL & diagnostic code = Intake Air Temp. Sensor Signal.

Diagnosis = Open or short in intake air temp. sensor signal for .5 sec. or more. (THA)

Trouble area = IAT sensor circuit or IAT sensor or ECM

 

[80t0ylc]

For location, according to the FSM, the IAT sensor is mounted to or part of the VAF (volume air flow) meter, which on later years is called the MAF. I'd check that electrical connector since it was probably disco'd when you did the HG work.
Edit: Confirmed. Chart in FSM show IAT sensor to be part of VAF Meter.

 

[jonheld]

Got it, is it necessary to try and chase the root cause of that fuse failure, does it have any relationship to the Mass Air flow unit? thx.

If the fuse is continually blowing then yes. If not, it's going to be hard to find. Considering the whole top half of the motor was off, it's possible that something shorted and took out that fuse during the procedure.

 

[dglenn]

thx for feedback, seems to be holding up ok over past few days. I did track down a new air flow assembly through cruisers.net. if not related will hold for spare. again, appreciate the input.