NO COMUNICATION WITH PCM PLEASE HELP.. - Third Generation F-Body Message Boards

slickvic · 08-06-2008, 02:26 PM

1) OKAY , I JUST FIRED THIS THING UP IT STARTED ON THE FIRST TRY. SOUNDS GOOD. BUT WHEN SHE REACHES TEMP THE IDLE STARTS TO GO UP AND DOWN. IF I DISCONNECT THE THROTTLE POSITION SENSOR THE ENGINE LEVELS OUT BUT STALLS WHEN I DEPRESS THE GAS PEDAL.

2) THERE IS A WIRE THAT COMES OUT OF THE PCM, A ORANGE/BLACK WIRE
IT'S LABELED PNP SIGNAL. I THINK IT A PARK NEUTRAL SIGNAL THE THING IS I CAN'T FIND A NEUTRAL SAFETY SWITCH ON MY VEHICLE( 88 CAMARO 5 SPEED ) I READ THAT IN SOME VEHICLE YOU NEED TO GROUND THIS WIRE OUT. I ALSO READ THAT GM RECOMMENDS THAT THIS WIRE NEEDS TO BE CONNECTED TO IT'S PROPER SPOT BECAUSE THIS WIRE CONTROLS EGR VALVE,THROTTLE POSITION,AND VSS SENSOR.

3) I CAN'T GET MY SCANNER ( SNAP ON) TO COMMUNICATE WITH THE PCM??
ANY INFO WILL BE VERY HELPFUL. I REALLY NEED TO GET MY CAR RUNNING CORRECTLY BEFORE SCHOOL STARTS. THANK VIC..

macdadyZ28 · 08-07-2008, 09:44 AM

Quote:

Originally Posted by slickvic

1) OKAY , I JUST FIRED THIS THING UP IT STARTED ON THE FIRST TRY. SOUNDS GOOD. BUT WHEN SHE REACHES TEMP THE IDLE STARTS TO GO UP AND DOWN. IF I DISCONNECT THE THROTTLE POSITION SENSOR THE ENGINE LEVELS OUT BUT STALLS WHEN I DEPRESS THE GAS PEDAL.

2) THERE IS A WIRE THAT COMES OUT OF THE PCM, A ORANGE/BLACK WIRE
IT'S LABELED PNP SIGNAL. I THINK IT A PARK NEUTRAL SIGNAL THE THING IS I CAN'T FIND A NEUTRAL SAFETY SWITCH ON MY VEHICLE( 88 CAMARO 5 SPEED ) I READ THAT IN SOME VEHICLE YOU NEED TO GROUND THIS WIRE OUT. I ALSO READ THAT GM RECOMMENDS THAT THIS WIRE NEEDS TO BE CONNECTED TO IT'S PROPER SPOT BECAUSE THIS WIRE CONTROLS EGR VALVE,THROTTLE POSITION,AND VSS SENSOR.

3) I CAN'T GET MY SCANNER ( SNAP ON) TO COMMUNICATE WITH THE PCM??
ANY INFO WILL BE VERY HELPFUL. I REALLY NEED TO GET MY CAR RUNNING CORRECTLY BEFORE SCHOOL STARTS. THANK VIC..

depending on how long you've run the car it may be trying to set a drive tune. It may stall or act funny for like 3 starts or around 30 miles of driving but it should be alright after that. Mine did the same thing after I put it together but it snapped out of it.

I didnt have to ground the park netural protection to work, so I dont know about that one =/

also, whats the situation with your obdII port look like? If i remember right its a 4 wire setup with a constant battery, 2 grounds and the signal wire coming from the computer. see if your setup matches what this looks like:

http://lt1swap.com/pictures/2_data_link_connector.gif

ghettocruiser · 08-07-2008, 10:15 AM

Another reference...

Give the grounds their own ground connections. GOOD ones. Dont just twist the wires together. I know it sounds weird... But some things are picky about grounds and power. Autometer gauges are one example...the LS1 PCM is another example.

J.

EDIT...wait... what motor are we talking about here....LT1 or LS1?

macdadyZ28 · 08-07-2008, 10:30 AM

Quote:

Originally Posted by ghettocruiser

EDIT...wait... what motor are we talking about here....LT1 or LS1?

LOL i just assumed ls1.

slickvic · 08-11-2008, 08:42 PM

THANKS FOR THE INFO.. STILL CAN'T GET MY SCANNER TO COMMUNICATE.
THE PROBLEM I HAD WAS THE BREATHER LINE GOING TO THE DISTRIBUTOR WAS CONNECTED TO A DIRECT VACUUM LINE.. I REMOVE IT AND TAPPED INTO THE FRONT OF THE AIR BOX. NOW SHE RUNS LIKE A CHAMP.. THE TRUTH IS, I COULDN'T BELIEVE THE AMOUNT OF POWER THIS BABY PUTS OUT. AND IN A TWO WEEK TIME FRAME.. NEXT YEAR MY 68 CAMARO WILL BE SPORTING AN LT1.