TPS voltage won't go lower than 4.95v..
- Thread starter TC93
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I get what you said about the OHM's reading being over 1.5 there is a problem. And if the ground circut(pin 46) in the EEC is whacked it would cause my symptons. I ran a test wire from pin 46 to a ground on the chasis and my TPS voltage is right. So it confirms what you guys where saying about the ground circut being open. Guess my question is, "Are there any other place(s) that pin 46 grounds beisdes in the EEC???
I checked all the grounds I know of, the one on the back of the head with the HEGO wire is(4 gauge ground strap to firewall also), the one buy the starter relay, that has the plug with jumper to NEG post on battery, and have a new ground cable from NEG to block. Also checked pin 20 to ground by the EEC, ran a contnuity test on it. Does that little bare wire that is with the EEC ground, run up and tie into the blk/wht wire to complete the pin 46 circut?
Trust me guys I do apreciate the help and understand what you guys are saying
, just not exactly sure what else to check????
well it all depends how you want to fix it. if you dont care how it looks, just splice into the black wire and ground it to the intake. if you want to fix it the "right way", read on.
you could have a problem at the black & white connectors at the back of the intake. or at the computer connector. i believe its internally grounded in the computer but you already tried another one so thats not it. you simply have an open in that wire somewhere. any damage to your harness?
you could have a problem at the black & white connectors at the back of the intake. or at the computer connector. i believe its internally grounded in the computer but you already tried another one so thats not it. you simply have an open in that wire somewhere. any damage to your harness?
This isn't my car, one I am working one for a guy. But the harness seems to be intact and original.
As for the jumper wire, I tied into the wht/blk (pin 46 gry/red on my harness) and ran it to the ground at the EEC and the TPS voltage return to normal. When I checked TPS with jumper wire in place, got .95 probing GRN & BLK wire. Tomorrow will se if check engine light goes out when its started.......
How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the
computer into self test mode. Since it is a dedicated ground, it passes through the computer
on its way to the computer main power ground that terminates at the battery pigtail ground.
It should read less than 1.5 ohms when measured from anyplace on the engine harness with
the battery pigtail ground as the other reference point for the ohmmeter probe. What sometimes
happens is that it gets jumpered to power which either burns up the wiring or burns the trace
off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an
experienced electronics technician can open the computer up & repair the trace if it burns
up and creates an open circuit.
How to test the wiring :
Measure the resistance between the black/white wire on each of the following sensors: TPS,
ECT, ACT, EGR and MAP/BARO. If you find one that is greater than 1.5 ohms, measure between that
sensor and pin #1 of the white 10 pin connectors. Pin #1 is the center pin and is labeled
sig-rtrn on the diagram
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the
computer into self test mode. Since it is a dedicated ground, it passes through the computer
on its way to the computer main power ground that terminates at the battery pigtail ground.
It should read less than 1.5 ohms when measured from anyplace on the engine harness with
the battery pigtail ground as the other reference point for the ohmmeter probe. What sometimes
happens is that it gets jumpered to power which either burns up the wiring or burns the trace
off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an
experienced electronics technician can open the computer up & repair the trace if it burns
up and creates an open circuit.
How to test the wiring :
Measure the resistance between the black/white wire on each of the following sensors: TPS,
ECT, ACT, EGR and MAP/BARO. If you find one that is greater than 1.5 ohms, measure between that
sensor and pin #1 of the white 10 pin connectors. Pin #1 is the center pin and is labeled
sig-rtrn on the diagram
no problem man...my problem was an intermittent high idle and engine light with TPS and EVP codes, caused by the bad factory splice in the orange wire (5v reference power) going to those sensors. i took it apart and soldered it, when i changed my fuel injectors. fyi, that factory splice it merely crimped, not soldered. then its covered with butyl (sticky rubber goo) to seal it. if you have things ripped apart already, you may want to do this as preventative maintenance.
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