TPS error code, screws holding TPS in place

[Amybirds]

Hello again,

Our 94 Q45 is acting up again -- The A/T error code says it's the Throttle Position Sensor but I'm going to do the FSM diagnostic to double check.

In the meantime, I'm hoping to clarify something:Are the two screws that hold on the TPS the two screws that I don't want to turn without a Consult to reset them? If that is the case, how do I go about replacing the TPS here at home without messing other things up?

Thanks!

For anyone that wants more details on the new issue: It's a 94 Q45, recently replaced the MAF (used) and the ECU (used) as well as all the belts and the battery. Things seemed to be going well (other than occasional Low Battery errors only when sitting at idle, but I think that' my alternator slowly dying and I don't have money to fix that right now).

Saturday, I drove it about 3 miles with no problems but then just as I got on the freeway, the RPMS would drop down super fast for a half second, then come back up, over and over till i had to pull over. I tried to get back going again a few times with the same results. So I sat there long enough to call my husband and AAA and then tried again (car still in drive the whole time, and idling solidly around 1000rpm when stopped) and the car worked fine but seemed to be in failsafe mode. Drove it about 20 miles to get it back home with seemingly no issues. Next time I got in the car it gave me a TRANSMISSION MALFUNCTION error, which went away. We checked the A/T codes, which said it was the Throttle Position Sensor, but then the second time we checked there were no codes and it said OK. Drove the car fine on Sunday for short errands. Husband got in car to commute to work today, car worked fine for about 25 miles, then it started acting like something was holding it back then acting normally, etc. Then it started having the RPM drops like I had experienced. And then, it started working fine again. Once again we have the A/T error code 3: Throttle Position Sensor

So, like I said above, I'm going to check out the TPS more, but if I need to replace the TPS, what do I need to know?

Thanks!!!-Amy

[elwesso]

Amy, did you get it figured out?

[Jberger]

You need to fix the altenator/low battery issue before trying to diag the TPS. None of the tests will be accurate without the electrical system having the proper voltage/amperage.

I've seen TPS errors that were really battery related before, so I'd fully charge the battery and test the altenator before you test the TPS.

Adjusting the TPS is dead simple with a Consult or one of the laptop based systems, and takes just a few minutes to complete. It's a pain without the proper tool, so I'd hold off on that until you are certain it needs adjustment.

[Q45tech]

All sensors must receive an absolute correct 5 volts for the voltage divider aspect to work............the 5 volts comes from ecu which must have 13.2 volts to correctly create the 5 volts.

The TPS creates a 11 step voltage [actually continuous but the ecu divides these steps [0.4-0.5, 0.5-1.0, 1.01-1.49, 1.5-1.99, 2.0-2.49 etc etc intoidle, 10%, 20% 30%,40% 50% 60% 70% 80%,90%, 100% desired load = desired power.

The desired power is then compared to rpm and airflow to show ecu real load.

Important that the throttle position [desired] and the actual eventually are close to preprogrammed numbers............why setting TPS position [= voltage] is important.

[texasoil]

Low battery voltage (poor connections, battery failure, slipping alt belt or dying alternator) will cause a host of intermittent and unrelaible 'failures' in all of the many electronic systems-and will overheat those costly modules and computers and cause total failure of them --- they will go up in smoke literally.

You HAVE to get the low battery voltage issue fixed PRONTO--the other stuff will most likely go away forever.