O/T: '96 Bonneville TPS code, keeps coming back?

1996 Bonneville SE, 3.8L non-supercharged. This darn thing has gone through 3 or 4 throttle position sensors in the last year or so. The newest one I put on less than two weeks ago. The AutoZone tech cleared the codes from the computer. Today the "check engine" light came back on, had it scanned, giving "TPS out of range" again.

Surely it wouldn"t have been that many bad sensors? Something else causing this code? Anything on a different circuit that interacts with this one that maybe is throwing it off?

Open to all suggestions. I"ll probably give this car to my mom and want to make sure everything is right with it before I do that.

As an aside, the AutoZone tech told me that they are not allowed to erase codes any more, he wasn"t supposed to do mine. Something about a tech cleared codes for a customer in TN or KY, ended up frying all the wiring in the vehicle. Now there"s a lawsuit and AutoZone HQ won"t let techs at any store clear codes. Anyone know more about this?

Thanks for your time,

Anthony

I went through the same thing with a '92 Olds 88 a couple of years ago. Same engine, so possibly the same TPS.

Basically, all a TPS is is a variable resistor with a winding and a wiper arm. The wiper arm follows the throttle and feeds info to the computer as to where the throttle is positioned, hence it's name. You probably already know this.

Anyway, the original on the Olds wore so there was a spot where the wiper didn't touch the winding and would give an "open" reading. I replaced it with one from NAPA, and the range of adjustment was outside what was called for. My Chilton manual gave resistance readings for the adjustment on the high end and low end. Checked the winding with an ohm meter, and it had entirely different resistance than the original.

For grins and giggles, I tried one from Autozone. Same thing. I tried an OEM one from GM, and it was off the other way. The OEM was made in Mexico, the Autozone in China, and the NAPA in Taiwan (I think). Everything I tried, the Check Engine light would come back on. I don't know what was so hard about duplicating a sensor with the same resistance as the original.

I then took it to the shop at the NAPA store where I bought the NAPA sensor, and they couldn't make their own sensor work.

By bending and filing, I finally modified both the NAPA sensor and the arm that contacts it and got it to adjust where Chilton said it should be. The light stayed out. Fuel mileage improved.

Wish I had better news, but that was my experience. At some point in the mid '90's they went to a TPS that had no adjustment, so I can't say for sure on yours.

Good Luck!

Your TPS is 5 volts input. The output signal is > .5 to < 4.5 volts. If you are not using after market sensors,wiggle test the wiring. You can test the TPS with a digital ohm meter. Slowly move the center and watch for the readings to change steady. An open will indicate a bad sensor. Has your connector on the sensor broken yet?

ANY problem in the 3 wires involved, between the 'puter and the sensor and various ground "issues" with have the 'puter seeing the sensor signal "out of range". could even be the 'puter.

check the wires at connecter
been known to brake inside the insulation

Need the code number to get a clue. There are several code numbers for TPS and each is telling a different story.

Explor and Goose are right on. You need to test the sensor with the digital ohm meter. What you want to do is unhook the sensor, measure the resistance while watching the meter and slowly opening the throttle plate. The reading should go up and down smoothly. It should never go both ways while opening the throttle. The other thing is having the correct voltage for idle position. If the sensor passes the test, check for damaged wires and connectors.
I guess I didn't know Auto Zone had "techs". I further don't understand how anybody could fry wiring clearing codes. Seeing as all that is involved is issueing a command with a scan tool, I say it is impossible to damage any wiring. The only way I can think of damaging wiring is if some idiot got to cutting and splicing, or the vehicle in question already had serious problems to start with.

The TPS is non-adjustable. Car runs fine.

I do have a digital ohm meter. On which pins do I check the voltage range?

I assume there is a replacement plug available that eliminates the possibility of wires broken inside the insulation?

Thanks everyone, I really appreciate it. Going to do some more work on it tomorrow.

Anthony

Check Engine light = MONEY as in parts sales

Clear Check Engine light = no sale NO MONEY

I hear a different lie each time I ask a customer why did they not turn the light off (clear codes) :lol: ,,, I could live with its against store policy,,, if it were such liability why hook up in the first place..

Maybe its a good thing,,, now I can charge to hook up and do my thang that is if you have not spent all your money chasing codes by swap'n parts :twisted:

Like anything else the answer is follow the money.

A ohm meter is a pizz poor way to check sensors,, never seen a puter that looked for the ohm reading from the TPS,,, it looks at voltage,,, Your out of range problem is gonna be hit and miss unless you know what the TPS voltage should be at any given operating condition,,, it rare a ohm meter would indicate a problem...

If you are gonna get anywhere the voltage reading would be real nice to know...