87 with 2.9 TPS testing

[Friendly_RangerMan]

I have an 87 Ranger, 2.9 4WD manual. I’m having issues with the engine, it likes to bog down and lose power at random times. Sometimes it will die when I pull up to stop signs. I read a lot of pages on TRS and that pointed me to the throttle position sensor…so I tested it, and I think I’m getting funky readings on the ground wire? It reads 60 or 70 mv. is the sensor bad or is it something with the computer?

Thanks,

 

[franklin2]

From the TPS ground to the vehicle ground you are getting voltage? Those grounds are different.

Do you have any codes for the TPS sensor in the computer?

 

[Friendly_RangerMan]

From the TPS ground to the vehicle ground you are getting voltage? Those grounds are different.

Do you have any codes for the TPS sensor in the computer?

Yes, I got a code 63 which is low voltage in the TPS circuit I think…I get voltage when I probe the negative terminal on the battery and the ground (black) wire on the TPS.

 

[franklin2]

I did a little research, pin 46 on the computer is a signal ground for the 5v supply. It's a black/white wire and what supplies the signal ground to the TPS.

The main power grounds are on pins 40 and 60. These are separate grounds that tie together and go directly to the battery negative with a smaller black wire going right into the large black ground cable.

But they say that pin 46 is tied to pins 40 and 60 internally inside the computer.

I would do some more experimenting. Do your ground testing again, but unplug the computer. Your readings may go really high then from the tps ground to the battery neg.

I would then be curious what type of ohm reading you get from pin 40 and pin 60 to the battery negative. Find that single wire connector for that ground wire that goes to the battery negative. That is the main ground for the computer system, and that single wire connector likes to corrode since it's near the battery. I do know for a fact if you have the engine running, and pull this ground connector apart going to the battery negative, the engine will quit right now. It's important.