TPS Check

[GMCJason]

Could somebody please explain to me how to check the TPS on my 1990 Suburban (TBI 350) using a multimeter? It won't pass emissions so I'm checking out a few things that were recommended.

I found the sensor and have been trying to follow the proceedure in my Chiltons manual but I'm either doing it wrong or the TPS is bad. I would assume that you need to disconnect the wire harness that leads into it otherwise I can't see a place to test. Although with it disconnected I don't see where the power would come from to get a reading.

I'll be the first to admit that electronics is not my bag but I'd like to learn. Can anybody help me out?

Thanks in advance.

 

[Bent77]

Using a multimeter, just speer the wires right above the connector. have had success doing it this way.

How long have you had it, has it had issues failing before? Also, how far off was it from failing, and HC or CO2?

 

[dyeager535]

I'd really recommend against puncturing the wiring. That only leads to problems down the road.

If you've got an autozone nearby, I'm told most have scanners you can use, you can simply look at your TPS voltage via the scanner, although not precise, it will give you a good idea.

Not sure which pins, but you can also use the audio multimeter alarm to detect dead spots in the sensor as you work it through the positions.

Scanner is by far the easiest way to test TPS voltage quickly.

 

[Thunder]

If you do spear the wires with a needle to get your readings and put holes in the insulation. Be sure to smear some silicone over the holes when you are done so water does not get in and corrode the wire.

 

[Big91RustyBucket]

Man I was thinking we were talking about TPS Reports.... Didn't you all get the memo?.......

 

[GMCJason]

Thanks guys. Maybe the easiest thing to do would be to take it to Autozone and use the scanner. That way I could check other sensors as well. I was hoping to figure it out using the multimeter though.

bent72 - I've had it for 2 years now and it had problems 2 years ago, too. I tuned it up then with plugs, O2 sensor, air filter and maybe some other things I don't recall. They've only got about 4500 miles on them. This year it has failed twice, both for HC and CO. The first time it failed I found a plug wire that had been burned through on the exhaust manifold but apparently there is more wrong.

Here are the numbers for the second test: HC @ 2500 - 512, HC @ idle - 548 with limits of 300. CO at 2500 - 7.56, CO at idle - 3.66 with limits of 3.00.

I checked for codes with the paper clip and there were none. I'm surprised that the O2 sensor isn't complaining about a rich exhaust with all those HCs.

 

[Bent77]

Yeah, sorry about the hillbilly pokin the wires trick, some of use don't shop at auto zone.

Anyways, looks to me like you computer is seriously pissed off. Normally don't see both running that high.

As for sending codes, that doesn't always work, especially if you have other issues like not getting a proper ground.

High HCs are often a way lean condition, which can be caused by a dead cylinder or bad plug wire, as happen to me. After fixing it, sometimes it takes a while for the computer to relearn and run better. Let me ask a friend of mine a few questions, maybe he will know...