SES, TCS, no tach, hard shift...Please help.

I'm not new to the forum but I did just get my GTP. The TCS Off light stays on (TCS doesn't work), the tachometer doesn't work and the tranny seems to be shifting hard but moreso when the SES light comes on. I've had the car for like 5 days. Got it cheap as a repo. The SES light came on then went back off then came back on and stayed on then went back off then came on and stayed again. It doesn't have any driveability problems but it kicked back five codes when it was on the Modis. One was a fuel pressure regulator switch circuit problem, another was an O2 sensor not switching, one was an EGR solenoid circuit problem, another was something with a possible fuel leak at an injector or fuel line on top of the motor, I can't remember the fifth. But when each individual code was tested they all passed and my mechanic cleared them. The SES light came back on when I was on my way home from the shop but it took a solid hour or more of driving on the interstate for it to come back. I have a few theories but I was wondering what you all thought about it. Any input would help. Thanks.

By the way my car is a 2000 Grand Prix GTP, 2 door, 3.8L supercharged.

You dont happen to have the code's??? It would help and give me a starting point.

Thanks

~Larry~

I'll get them on here ASAP. Thanks man.

I will also need the 3rd,8th and 10th digit in your VIN #

Thanks

Hey Big L this is getting weirder by the minute. After the SES light came back on today I took it to Auto Zone to get the codes for you and two completely different ones came back, not one of the original first five I think. The first is P0172 and the second is P0742. My VIN digits you need are: 2,1 and Y. (They are in order: 3rd,8th,10th.) The way it acts it seems like it does need an O2 sensor and a tranny service but, the PCM has thrown unrelated, random codes as far as I know. Could my PCM be bad or need a flash/update/reprogram? Thanks again.

P0172 Fuel Trim System Rich Bank 1,the troubleshooting all points to the intake side of the engine. Check MAF screen, inlet tube for collapsing or obstructions, inspect the throttle body bore, throttle plate and IAC passages for coking and foreign objects. Disconnect the vacuum hose from the fuel pressure regulator and inspect the hose for presence of fuel.If all else fail's then you maybe having a problem with the fuel pump,may want to test fuel pressure.


P0742 Torque Converter Clutch Circuit Stuck On .Im not sure on this one (I hate tranny work),give me sometime and ill get back to you.

Got a sick daugther with the flu and a 103 temp.Thanks Jim/Kustom kid I told ya so :lol:



~Larry~

Thanks Big L. I'll run that stuff by my mechanic and get him to check it out for me.

P0742 Torque Converter Clutch Circuit Stuck On

It maybe one of the devices that either apply or turn off the TC is possibly bad. TCC control valve, TCC feed limit valve, TCC regulator apply valve, TCC PWM solenoid valve, pressure regualtor valve. Could be wiring problem between computer and trans, disconnect PCM connector C2(with battery disconnected), disconnect trans connector and, using a meter, check between pin u on trans connector and ground for a short, should read open. That wire is the TCC release switch input, if it's grounded, the PCM will think the TC is always applied, if so it sets 742 and commands the TCC on at maximun capacity and disables shift adapts.

Good luck,as this one maybe costly and may require a rebuild.

~Larry~

could be a bad wheel speed sensor in one of the hub bearings. When the computer gets a funky signal from one or more wheel speed sensors, it can cause all kinds of crazy trans shift, trac off, ses lights to go off.

Thanks guys. I just dropped it off at the shop so I should know what's up soon.

Big L got the bases covered but I can add one more thing for your mechanic to ccumlatorcheck out. below the air filter box check the wiring next to the AC accumlator for chafing. This is a well known area for all kinds of problems. The engine torque causes the wiring to rub on the AC accumlator.

Thanks Flatrater I'll run that by the guys too.

I got her in the shop fellas. I think me and the guys figured out what it was...TFP switch valve in the transmission valve body. We are gonna swap it out with a new one and toss a tranny flush at her. All the electronics checked out and we are gonna put two new 02 sensors on to smooth out the engine so it will hit the shift points perfectly so we can tell if we got it fixed. Hopefully this is all I need to do. No tranny rebuilds please. Thanks guys.

V8soldier,

Just wondering if your car is fixed and What the mechanic did to fix the problems.

Yeah, we figured out what it was marine. It was the TFP switch valve in the transmission valve body. After we replaced that and did a tranny flush it was fine. The other code I had was an O2 sensor and a vac leak. I've put on both O2 sensors and I'm about to put on a new MAP sensor and EGR valve. The tach is still a mystery though. The TCS light we think is the switch itself in the dash, it doesn't do anything at all when we push it and we have fixed the tranny problem and tested the circuits so that has to be it. Thanks to everybody for the input.