Hello! I could use some help with a throttle position sensor testing. My 1998 Blazer is shifting hard from 1st to 2nd and I read that a bad TPS is often the culprit. I went to test the three wires at the connector, found the 5V signal wire, but the other two wires are both showing 19 volts?! Neither rings out as a ground ( I tried a continuity test to the ground strap ). I don't understand how I can get a voltage as high as 19v, and also not get a continuity to ground.

Any help you can provide is greatly appreciated.

Thanks

 

Get a decent scanner if you want to work on a Blazer (and probably a new multimeter as well). Monitor the throttle position that the PCM is seeing. Closed throttle is 0, Wide open throttle is 100%. should be smooth transition throughout the range. easy peasy.

In a nutshell, BAFX Bluetooth OBD2 adapter as sold on Amazon and Car Gauge Pro on an Android phone will work with your 1998 Blazer for about $30. Dash Command will also work, and also has a version for iPhone - but you will need to pay $10 extra for each car to get extended PIDs. Dash Command does work on 1996 and 1997 Blazers, where CGP does not. Torque Pro works OK too (at least on 1998+ Blazers), but does not do cam sensor retard on any of the Blazers. If you go iPhone then AFAIK you will need a Wifi OBD2 adapter.

Harsh 1-2 shifts are common on 4L60e transmissions (in more cars than just Blazers). Depending on how harsh it is, it may be normal. MAF sensors and engine performance in general can also have an effect.