Electrical mystery

[Insanejughead]

I just about have my pickup running again, and this time I will have the '87 LA3 in it, but I'm having problems with something that I don't understand.


When checking the SIG and SIG RTN on the VAM and TPS, I'm getting a reading of .07-.08 millivolts.


My dad and I both have triple checked (several times) the pinouts for the computer and all of the sensors.

Any ideas on what could be going on?

 

[Insanejughead]

Problem hopefully discovered.

I completely removed the wiring harness and unwrapped all of the sheathing and tape. I found, around the junction of a Gry/Red wire (Pin 46, Sig Rtn for me), a split in the wire's insulation. I found it after I had completely stripped that section of harness, so I don't know what or where it may have been rubbing and grounding out the computer's signal.


Now I'm streamlining my harness as good as I can, so that when I put it back in, there won't be any jumbles anywhere.


One more question for all you LA3 guys out there: What fuel mileage are you getting and from what chart did you use information about the pinouts?

 

[kaytbugsdad]

I'm getting between 16-18 mpg with my setup...... 87 TC engine (all stock), 89 V8 Mustang T5, 4.10 gears, 245/45r17's on Cobra wheels......

 

[Insanejughead]

That's actually not bad, especially considering the higher gear ratio in the transmission and the lower ratio in the diff.


What pin-out sheet did you follow when doing the swap?

 

[scotts90ranger]

I get 9-18mpg depending on conditions, if I'm going balls out for the whole tank it'll be in the 9mpg range, if I'm just driving highway and behaving it's in the 18mpg range assuming the engine is cooperating at the time, will probably change one way or the other after I rebuild the engine soon.

 

[scotts90ranger]

I used the diagrams in the tech library and some from google searching

 

[Insanejughead]

Thanks, Scott. I've found a few mistakes in the diagram in my Chilton's book, so I like to have backups to go off of.

 

[kaytbugsdad]

I used the same set-up that Scott did....... The pinouts were accurate, and my truck drives excellent, even passed California's strict smog program!!!!!

 

[Insanejughead]

Schaweeeeeeet!