TPS keeps messing up?
11-18-2016, 04:25 PM
#21
The problem I had before was the transmission was shifting VERY hard into drive and reverse - so much so the rear wheels chirped if I didn't hold the brakes on hard. Local diagnostics place looked at the TPS after recommendation from ClineBarger in the auto transmission part of this forum and as suspected the TPS was reading well above 0% at idle - 7/8% and so the PCM was increasing line pressure in the transmission. He also found that opening the throttle just a tiny amount made the TPS Reading drop back to 0% and then immediately back to 7% where it would continue to rise normally. Other than that, the actual driving experience was ok and you wouldn't notice any issues (TCC worked fine with this dodgy original TPS). So I ordered one from a uk supplier which turned out to be a cheap Chinese one which didn't solve anything as you can read above. I then got an AC Delco pro one which broke sometime in the 12 hours from fitting to when I found it broken the next day (fell to pieces and was going open circuit across the potentiometer - returned to rockauto for analysis!) this third TPS is a Standard branded one and seems much better quality than all the others I've tried.
**update** - got home from work today and checked TPS signal voltage and decided to check it using the connector ground rather than the battery negative post. The voltage measured 0.42 volts doing it this way and so I reset to 0.55. It seems the voltage between connector ground and signal wire is about 0.1 volts lower than signal wire to battery negative. I assumed that the PCM was seeing the wrong voltage because I've been setting it unknowingly too low. There must be a higher resistance in the connector ground compared to going straight to the battery. Relearned and went for a drive and the TCC is working again! Turned the engine off and on multiple times and the TCC works each time. Not been in this situation for some weeks so I'm hoping this is fixed. I will report back if the fault comes back.
**update** - got home from work today and checked TPS signal voltage and decided to check it using the connector ground rather than the battery negative post. The voltage measured 0.42 volts doing it this way and so I reset to 0.55. It seems the voltage between connector ground and signal wire is about 0.1 volts lower than signal wire to battery negative. I assumed that the PCM was seeing the wrong voltage because I've been setting it unknowingly too low. There must be a higher resistance in the connector ground compared to going straight to the battery. Relearned and went for a drive and the TCC is working again! Turned the engine off and on multiple times and the TCC works each time. Not been in this situation for some weeks so I'm hoping this is fixed. I will report back if the fault comes back.
11-21-2016, 05:24 PM
#24
It's a standard motor products one - TH149 is their part number.
Being uk based means I usually have to order from Rock Auto, Summit or Jegs. Luckily though one of the UK American car parts suppliers we have over here, has these as a stock item.
The SMP one says made in the USA compared to the AC Delco one which was made in Mexico. I guess it does make a big difference...
Being uk based means I usually have to order from Rock Auto, Summit or Jegs. Luckily though one of the UK American car parts suppliers we have over here, has these as a stock item.
The SMP one says made in the USA compared to the AC Delco one which was made in Mexico. I guess it does make a big difference...
12-20-2016, 06:53 PM
#31
Originally Posted by CoreyD
Little update: I got the SMP TPS and I test fitted it on my TB and as I pulled it off it fell apart...so looks like I'll be looking elsewhere