Fixed - Code 22 TPS Voltage to Low - Hard Code + Stalling

[Dutch2005]

I'm having problems with the TPS circuit in my Bonne and I'm stumped.

I know there is alot to read, but please help.

History:
When I put on my rebuilt S/C about a 1 1/2 years ago I cleaned the throttle body with the sensors removed.

After reassembly I started seeing Code 21 TPS voltage to high, so I backed it off and started seeing code 22 TPS voltage to low, so I set it back to its original position and have been driving it like that ever since.

At the time I checked the sensor with a DMM for resistance, voltage and ground and everything checked out.
I even used a scan tool and everything was with in specs.
It kept throwing codes 21 and 22, but the car ran fine.

Currently:

I got tired of seeing the check engine light coming on and off with its two usual codes 21 & 22 so I decided to buy a new Delco TPS from the Dealer.

I bench tested both of them with the DMM for comparison before installing the new one and they were both very similar but the resistance on the new one was slighty different (higher resistance), when moving the arm.

So on goes the new one and the car started throwing code 22 (voltage to low) and I was only getting 80 % with the scantool at WOT.
I almost didn't make it to and from work for the next two days as the car was hesitating and stalling at traffic lights.

So the next day after work I put the original back on and its still doing the same thing and throwing code 22.

I printed out a bunch of trouble shooting and wiring diagrams from Mitchell and tested everything from the PCM to the TPS and the CTS but I can't find anything wrong.

I also tried providing the TPS with its own ground straight off of the Battery post and no difference.

When I erase the codes with the scan tool they are back right away without even starting the car.
I can't get rid of code 22 or the hesitation problem.

I also disconnected the battery for about 15 minutes.

I noticed when i had the scan tool hooked up, that it shows very low voltage but the percentage of throttle is fairly accurate.

I'm thinking maybe a bad PCM/ECM.

What else is tied into this circuit or what else would cause this code ?

I'm stumped any ideas or suggestions ?

Thanks in advance,
Dutch

[Jrs3800]

So if you were to disconnect the battery, and reconnected the code would return as soon as you turned the ignition on?

[93RedSled-SSE]

So the next day after work I put the original back on and its still doing the same thing and throwing code 22.
I'm thinking maybe a bad PCM/ECM.
What else is tied into this circuit or what else would cause this code ?

Loose fitting (female) pins in the wire side of the connector plug at the PCM will drive you crazy with intermittent problems. No offense, but female pins in the PCM connectors and ignition ckt for this vintage are crap.

One thing you can do is make sure you verify the +5 volts at pin A (gray wire) of the TPS connector WHEN you are getting the code 22.

Another is looking for a loose plug connector pin on the PCM plug(s).
It is child's play checking for loose female connectors. Here's the down and dirty:

• Do you have a standard sized, bare metal paper clip? They are just the right size. Straighten one end out to use as a test tool.
  1.Unplug the (I believe it is the middle) connector on the PCM. It is smallest of the 3.
  2.You will especially want to check pin B3 (5 v out) grey wire and B10 (TPS ref. In) Dk Blue on the connector.
  3.Basically, compare the fit of the paper clip into the female pins with others. Of course, the problem is if one is not fitting as tight as the rest. Just use a light touch, pretending you are a safe cracker.
  4.On the connectors, the outer rows are the holes for the pin locks. The inner rows are actually the female pins.
  5.The loose connector pin(s) will need to be crimped in to fit tighter, either by temporarily pushing the pin out the back (it has a lock) or trying to tighten it while still in the connector.
  If needed, I can explain how to release the pin, which will require a small jewler's or eye glass screwdriver or two.

Try this before, possibly, wasting your money on a PCM that may not fix the problem permanently.

[Billha]

Checking the pins on the TPS connector is certainly a good idea; they may have spread apart a bit. Or maybe there's a bad crimp connection to one of the wires. If you were to use a scan tool to monitor the TPS voltage while someone moves the connector and/or each wire, you'd easily know for sure.

[Wes]

I would get that scanner on it and check the tps voltage. spec at idle is between .33 and .46 volts. wot is 4.1-4.2 volts. if higher than 4.8, then the tps needs to be replaced. but most likely just needs to be adjusted.

[Dutch2005]

Thanks for the help and suggestions.
I figured out what the problem was and fixed it.

For some reason the ECM/PCM has become more picky about the minimum voltage that it wants to see at the TPS with the throttle closed.

I had it set at 0.0 volts with 0 % throttle with the KOEO (Key On Engine Off)
This is what was causing it to throw codes.

I ended up figuring out the problem by taking off the throttle body with everything pluged in and making slight adjustments to the TPS while watching the voltage on the scan tool and checking and re-checking for codes.

I ended up setting the TPS to .22 volts (the lowest the ECM would accept) with 0% throttle and 100% at WOT

The best thing is that the car is more powerful than ever before, no more stalling and check engine light coming on and off while driving.

Anyone know what the minimum voltage the TPS is supposed to be set to ?
Does the FSM say ?

Thanks again,
Dutch

[Wes]

I would get that scanner on it and check the tps voltage. spec at idle is between .33 and .46 volts. wot is 4.1-4.2 volts. if higher than 4.8, then the tps needs to be replaced. but most likely just needs to be adjusted.