16197427 - No reading from Map signal.

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10-13-2016
notime2d8

16197427 - No reading from Map signal.

Hey, needing some help/ideas as I am stumped. I'm doing a Carb to TBI swap with the 7427 PCM. I thought I tested everything before I installed it into the vehicle but I can not get a map reading in tunerpro. All of my other sensors work and I checked the wires, I do get ground and 5v, but when i apply 5v or ground to the signal wire I get no change on the reading. And when it was all plugged up with the Carb still, i got no reading... don't know where to look next. I also tried another working PCM, same thing.
10-14-2016
Nasty-Z

Quote:

Originally Posted by notime2d8

Hey, needing some help/ideas as I am stumped. I'm doing a Carb to TBI swap with the 7427 PCM. I thought I tested everything before I installed it into the vehicle but I can not get a map reading in tunerpro. All of my other sensors work and I checked the wires, I do get ground and 5v, but when i apply 5v or ground to the signal wire I get no change on the reading. And when it was all plugged up with the Carb still, i got no reading... don't know where to look next. I also tried another working PCM, same thing.

MAP signal to the PCM is on pin B13 , I would start by checking for resistance in the wire (Lt Green) leading from the MAP sensor to the PCM , perhaps there is a cut or broken spot in the wire not allowing the signal to reach the PCM.

Ground is pin B4 (Black wire) and +5v reference is pin E14 (Grey wire) , I know you said you had both of these but whole you are checking wires a double check might not hurt.

TOM
10-16-2016
notime2d8

Quote:

Originally Posted by Nasty-Z

MAP signal to the PCM is on pin B13 , I would start by checking for resistance in the wire (Lt Green) leading from the MAP sensor to the PCM , perhaps there is a cut or broken spot in the wire not allowing the signal to reach the PCM.

Ground is pin B4 (Black wire) and +5v reference is pin E14 (Grey wire) , I know you said you had both of these but whole you are checking wires a double check might not hurt.

TOM

Thanks, I think i'm going to cut the wires close to the PCM and run 3 new wires. I converted an old 87 harness to the 7427, everything else works but the map. If running new wires don't work, i'm going to call it and order a new one for $290 unless someone on here sell me one cheaper.....
10-21-2016
Woods

Quote:

Originally Posted by notime2d8

. If running new wires don't work, i'm going to call it and order a new one for $290 unless someone on here sell me one cheaper.....

A little confused, new what?
10-21-2016
notime2d8

Quote:

Originally Posted by Woods

A little confused, new what?

A new stand alone harness. And I couldn't get it working after running 3 new wires. I probably have a short somewhere. I'm just going to order a new 7427 tbi harness that has the 4l80e wiring for $290.