Heres the test you must do for it with the key to Run. Unplug the TPS and measure the voltage between Brown/White wire and the Grey/White wire you are supposed to have 5.0 volts. On mine i have only 4.93 volts.
Plug it back and back probe Grey/Red wire and Grey/white wire you are supposed to have less than 1.5 volt. Turn it to wide open throttle and it supposed to have 5.0 volts again but also there i had only 4.93 volts. When it was unplugged I measured it but instead of putting it on grey/white wire i did it on the negative of battery it gave me the 5.0 volts I needed.
Made the same with other tests and it gave me the good voltage. So thats why we say that there a lost of voltage due to ground resistance and in this case what is could be considered as a ground even if it go back to EEC is the Grey/white wire. Just to be sure thats not the TPS that was more resistant than it supposed to be I unplugged the connector behind the alternator
the one with lot of wires.
The one with male pins is the one that the voltage come from so again i tested it the Brown/White wire plugged on the negative of battery gave me 5 volts but on the Grey/white wire on the same plug that go back to EEC it gave 4.93 volts again.
Now like that we are sure that its not other wires or tps that have too much resistance. Problem solved its the Grey/White "ground" wire that is more resistant than it should be. Lots of first gen explorer have the same problem.
For my part it gave me 3 codes. First a TPS out of range, second is a HEGO, and third is a false pcm EEC signal. In ford manual shop for first gen explorer and other 4.0 OHV its written a faulty tps or tps circuit out of range will make the engine run richer and give a HEGO oxygen sensor signal at the same time.
This problem will be solved when the tps problem will be solved. For the faulty pcm signal it come from the wrong voltage that is sent back by the TPS grey/white wire. For my part i will cut the grey/white wire at the TPS connector start a wire from there pass it through the firewall cut the other end of the original wire at the EEC pcm and put my new wire there.
Problem of "Ground" solved without having the problem to take off all the wires and their protectors. I dont know why but from 1991-1994 they had all the same grey/white wire problem.
Plug it back and back probe Grey/Red wire and Grey/white wire you are supposed to have less than 1.5 volt. Turn it to wide open throttle and it supposed to have 5.0 volts again but also there i had only 4.93 volts. When it was unplugged I measured it but instead of putting it on grey/white wire i did it on the negative of battery it gave me the 5.0 volts I needed.
Made the same with other tests and it gave me the good voltage. So thats why we say that there a lost of voltage due to ground resistance and in this case what is could be considered as a ground even if it go back to EEC is the Grey/white wire. Just to be sure thats not the TPS that was more resistant than it supposed to be I unplugged the connector behind the alternator
the one with lot of wires.
The one with male pins is the one that the voltage come from so again i tested it the Brown/White wire plugged on the negative of battery gave me 5 volts but on the Grey/white wire on the same plug that go back to EEC it gave 4.93 volts again.
Now like that we are sure that its not other wires or tps that have too much resistance. Problem solved its the Grey/White "ground" wire that is more resistant than it should be. Lots of first gen explorer have the same problem.
For my part it gave me 3 codes. First a TPS out of range, second is a HEGO, and third is a false pcm EEC signal. In ford manual shop for first gen explorer and other 4.0 OHV its written a faulty tps or tps circuit out of range will make the engine run richer and give a HEGO oxygen sensor signal at the same time.
This problem will be solved when the tps problem will be solved. For the faulty pcm signal it come from the wrong voltage that is sent back by the TPS grey/white wire. For my part i will cut the grey/white wire at the TPS connector start a wire from there pass it through the firewall cut the other end of the original wire at the EEC pcm and put my new wire there.
Problem of "Ground" solved without having the problem to take off all the wires and their protectors. I dont know why but from 1991-1994 they had all the same grey/white wire problem.
