I have a 93 seville sts that shifts very hard and the cel comes on. The code its throwing is p076, but if I clear the codes from the pcm then the light goes away and it shifts great, for a mile or so. I know a little about the car (just purchased it a couple days ago.) Since clearing the codes makes it shift smooth, this leads me to believe the solenoids are fine and its my pcm thats faulty. Is there some way I can test my pcm? Or should I be looking somewhere else? thanks for the help!
-Zak

 

You must have the 4.6 Northstar engine?
I don't show a P076 for the 4.6, so I'll assume it is the Northstar w/4T80E trans.
P076 is for the EPC, or electronic pressure control solenoid(also called PCS, or pressure control solenoid). Clearing the code will allow the trans to shift properly until the code resets. The code resetting means there is a problem in the EPC circuit, or the EPC solenoid itself. You would need to dis-connect the trans connector, and check the resistance of the solenoid first. If that checks ok, then you would be looking at testing the harness from the trans to the PCM(powertrain control module), to see if there is a short, or an open circuit. If the solenoid, and the wiring test good, then you may have a bad PCM. One problem we have seen on these is corrosion of the terminals in the connector itself. Sometimes, just un-plugging, and plugging it back in "fixes" the problem....that's certainly worth a try. The connector is kinda hard to get to, especially from the top. It comes out of the trans toward the passenger side of the car, under the water pump. I have also seen several with the wiring of the connector damaged, or the insulation deteriorated to the point of having bare wires touching. MY suggestion, if you would like to try to do all you can before taking it to a transmission shop, is to unplug, and reconnect the connector first, but take a good look at the terminals inside the connector for any signs of corrosion(green, or chalky white stuff). Look carefully at the actual wiring coming out of the the connector for any signs of damage.
If you have the equipment(ohm meter, or good multi-meter) to test the solenoid, you could do that also.
Otherwise, my only recommendation would be to take it to a trans shop for further testing....as much as I hate to suggest that....and I work at one.
hth

Test Condition(s)

1. Codes P016, P086 and P089 not set.
2. Engine running.

Failure Condition(s)

1. Difference between commanded and actual transaxle pressure control solenoid current 0.16 amps or greater for 1 second.

OR

1. Transaxle pressure solenoid energized at 100% duty cycle for 3 minutes or more.

Action Taken

1. PCM turns 'ON' the 'SERVICE ENGINE SOON' MIL.
2. PCM deenergizes the transaxle pressure control solenoid.
3. Torque management is disabled.
4. Transaxle shift adapts are maintained at current levels.

Notes on Fault Tree

1. Checking for an open in the transaxle pressure control solenoid circuitry. If resistance is 8 ohms or greater, there is an open in circuitry.
2. Checking for a short to ground in the transaxle pressure control solenoid circuitry. If resistance is 100 ohms or less, there is a short to ground in the circuitry.
3. Transaxle pressure control solenoid circuitry is OK, so fault is either intermittent or the PCM is bad.
4. If the resistance measures greater than 8 ohms check for an open inside the transaxle on CKT 1228, CKT 1229 or in the transaxle pressure control solenoid. If resistance is 8 ohms or less, check for an open between C130 and the PCM in CKT 1228 or 1229.
5. If the resistance measures 100 ohms or greater, check for a short to ground between C130 and the PCM in CKT 1228 or CKT 1229. If resistance measures less than 100 ohms check for a short to ground inside the transaxle in CKT 1228, CKT 1229 or in the transaxle pressure control solenoid.