Hello everyone I am new to the forums.

I have had some problems of the car starting sometimes, the other times it would just crank and crank but not catch. I seemed to have fixed that problem with the following parts:

New AC Delco Fuel pump
New Fuel filter
New ignition switch
New Fuel pump relay
New oil pressure switch
Tested the crankshaft position sensor and it came out to 777Ohms (haynes manual said 500-900 is normal)

Now the new problem is that when I am driving normal it is fine but if I floor it, the car stalls. I tried hooking my dads snap on scanner tool and the communication between my OBD port and the scan computer could not connect. Is that a symptom of a bad problem?? I have never had a car not be able to connect to a scan tool.

Could the symptoms of stalling under heavy acceleration and no OBD port communication be linked?

If you need more info please let me know, I am stumped!

Auto or Manual?

Manual is OBD 1
Auto is OBD 1.5

The scanner is probably OBD2.

Is your check engine light on?




PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO

It is a manual, I hooked the GM-1 Connector up to it so it would fit.

The CEL is only on when the key is in run position, when the car is running there is no CEL on.

You need to have a seperate power source for obd1 going to the scan tool. Should be an adapter for cigarette lighter or something like that. Then pull the codes.

I have had this problem before..... Because I had a 95. This is an OBD1.5 system this year and the connector under the dash fits a obd 2 scan tool, however it uses a obd1 operating system. You have never connected a scan tool to it and had it scan the car correct??

I haven't had the car long so I have never hooked a scan tool up to it before. I called my dad and told him that it was an OBDII connector but the system is OBD1, I told him he should have some special adapters for his snap-on scanner and he knew exactly what I was talking about. So I will run it here in a few hours. Thanks for the clarification on that guys!!! I thought maybe my PCM was toast lol.

Hopefully it has some codes on it and its not blank, I would like to fix the issue of the car shutting off when accelerating heavy.

Maybe your air charge temp sensor. The reason you can not communicate with the obd is because it is "1.5" obd. If you had a automatic, then it would of been OBD2. I have the same year and same manual trans.

I cannot get this Snapon Modis scanner to connect to the cars computer. My dad owned the car before and he has had the same scanner connected to it before. I had it plugged into the cigarette lighter for backup power and even had the correct plug the scanner told me to put in. No communication when trying to pull any data or codes.

cig. lighter have power? check the fuse

Yes cig. lighter is operational...The power cord going to the lighter has an LED light on it confirming it works, plus I can use cell phone charger through it.

Well, then its either a bad dlc or something wring with the scan tool. I think its pin 4 and 5 on the dlc, but not at all sure...can anyone verify where to check for good signal wires?

was wondering if the exhuast is restricted. you could remove the front 02 sensor from the exhaust (should only be 1 on obd1) and test drive to confirm. The engine will exhaust out the open hole by-passing a clogged cat.

i think the dlc wires are:
orange wire, pin #16...hot at all times 12v supplied from cig fuse
black wire, pin #4 to chassis ground
black/white wire, pin #5 pcm ground
purple wire pin #2, class 2 serial data line
tan wire pin #9, uart serial data line

if the dlc feed circuit has power... pin 16
check the serial data lines and uart lines for open, short to ground and short to voltage.

any ipc problems? The ipc is the gateway module for this platform. Are all the telltale lights illuminated at koeo? ie. check oil, low coolant, oil pressure, volts, tach and temp guage if equipped?

Its weird how the scanner could communicate with the car a few months ago then I had these problems and now I can't connect to the car.

I will start with the DLC wires, I need to find a printout of the OBD port so I know which pin is what when testing it.

From my knowledge the IPC is working correctly, all the telltale lights illuminated at koeo.

More explanation about testing the DLC would be great like which multimeter probe (pos/neg) on what DLC pin # and if I should be looking for a certain voltage amount.

Thanks a bunch!!!

Could these problems be from a recall about "Corrosion/Moisture Entering the PCM" ???

Here is an Update:

Orange wire pin #16 - Confirmed 11.86V using pin #4 and pin #5 grounds, also using seat rail bolt as a ground.

Purple wire pin #2 - No voltage at all using pins #4 & pin #5 as ground and seat rail bolt as ground.

Tan wire pin # 9 - Confirmed 3.70V using pins #4 & #5 as ground and seat rail bolt as ground.

Shaun Longbottom wrote:Could these problems be from a recall about "Corrosion/Moisture Entering the PCM" ???

you better inspect the pcm...some of my coworkers have seen modules that you could see into; opened up from the corrosion

Well here are pics of the corroded PCM. I am going to try swapping it out with a new one to see what the results will be. You think maybe I should open it up to see if I see anything out of the ordinary like something shorted out or burnt?

No signs of moisture inside the PCM, nothing smelled or looked burnt up. Hopefully a new PCM will still fix the cause of my car!!!

seal your replacement pcm as per that tsb!

I am about to drive around with the new one in and still see if it stalls under heavy acceleration..If it does I am going to reseal my old PCM, and then the only thing I can think of to check would be fuel pressure??

while the new pcm is in; see if your scan tool can communicate with the pcm.

New PCM connected, the scan tool could not communicate with the PCM. With the new PCM in the car, under heavy acceleration the car still falls on its face and shuts off. Sealed old PCM and put back in the car.

I am thinking maybe it is fuel pressure? Could be a faulty fuel pump from AC Delco. So I am going to check fuel pressure this weekend.

Any other suggestions?

get the battery/alternator/wires tested, and sice you put a new relay and other things, I assume the plugs and wires are real good and good gap, right?

if the obd port is out of order, can the computer still turn on the CEL?

If it can't even generate codes to display or store or turn on the dashboard CEL, then it could be lots of codes, emissions codes, misfire codes.

Is there an easy code, or some way to force the light to turn on, like unplug the fresh air hose or a certain thing?
Just to see if you can get the dashboard light to let you know it's able to.

If I assume you really do have obd 1, is that the one where years ago I used to be able to plug a paper clip or small wire between 2 pins at the connector,
and have the codes blink the dashboard light? Like a code 55 would blink the light 5 times, pause, then 5 times. Maybe that was even before obd 1, I
don't know.

Yea, key on engine off and the cel should be on

the pcm wiring harness can be bad where it runs along the front of the car. Check for opens, short to grd and short to power on the class 2 and uart lines from the pcm to the dlc. If you want ot do this and need pin out #'s let me know.