(Fixed) 92 Explorer 122 Trouble code (this guy got super lucky)

[unometooo]

This weekend I replaced all the intake gaskets and the valve cover gaskets. When I put everything back together I had a CEL. I noticed that I am also down on power. I ran the codes and I am getting a 122 and a 998. I have used my multimeter and checked the current going thru the TPS and I get 5v when I check the gray with red strip against the brown wire (I think that's what color it was). At idle I am getting .9v when I check between the two gray wires and the more I ramp up the throttle, it goes up to 6v. I am at a lose, I think those readings are within parameters. So what else could cause the 122 code? I know the 998 is a limp mode code.

 

[Maniak]

When testing the TPS voltage, compare the Black wire (ground) on the TPS to the other 2 wires.. One will give you 5v (Orange I think) and the other should be < 1v. IIRc, .96 is prefect but somewhere around .8v to 1v is what you expect.

Also, just to nit-pick.. You checked the voltage at the TPS, not the current going through it.

Assuming all those #'s look right, verify you got all the ground wires back. The ECM needs a good reference (ground) to compare against otherwise it will get funky readings.

~Mark

Edit: Here is a thread with good info on setting the voltage which has the colors listed etc..
http://www.explorerforum.com/forums/showthread.php?t=79362

 

[unometooo]

When testing the TPS voltage, compare the Black wire (ground) on the TPS to the other 2 wires.. One will give you 5v (Orange I think) and the other should be < 1v. IIRc, .96 is prefect but somewhere around .8v to 1v is what you expect.

Also, just to nit-pick.. You checked the voltage at the TPS, not the current going through it.

Assuming all those #'s look right, verify you got all the ground wires back. The ECM needs a good reference (ground) to compare against otherwise it will get funky readings.

~Mark

Edit: Here is a thread with good info on setting the voltage which has the colors listed etc..
http://www.explorerforum.com/forums/showthread.php?t=79362

I did check the voltage going thru the sensor, I put paper clips in the back side of the plug while it was plugged in. There are three color wires, gray with red stripe, gray with white stripe and I cant remember the third color, brown or black i believe. the two outside wire gave me 5v, the two gray wire is what I checked while plugged in and if I recall correctly it gave me .8v at idle and 5-6v at full throttle (thru the sensor).

 

[Maniak]

I did check the voltage going thru the sensor, I put paper clips in the back side of the plug while it was plugged in. There are three color wires, gray with red stripe, gray with white stripe and I cant remember the third color, brown or black i believe. the two outside wire gave me 5v, the two gray wire is what I checked while plugged in and if I recall correctly it gave me .8v at idle and 5-6v at full throttle (thru the sensor).

When you say you checked the two outside wires and got 5v are you saying you put the negative lead of the DVM on 1 outside wire and the red lead on the other outside wire or did you have the DVM black lead on ground and you put the read lead on each outside wire and got 5v on each?

AND, are you saying you have 4 wires on your TPS? That is what I am reading but there should only be 3 wires on the TPS on a 1st gen.

~Mark

 

[unometooo]

When you say you checked the two outside wires and got 5v are you saying you put the negative lead of the DVM on 1 outside wire and the red lead on the other outside wire or did you have the DVM black lead on ground and you put the read lead on each outside wire and got 5v on each?

AND, are you saying you have 4 wires on your TPS? That is what I am reading but there should only be 3 wires on the TPS on a 1st gen.

~Mark

no, only 3 wires. I read this thread for a bronco and my wire colors match these colors in this thread.

http://autoforums.carjunky.com/Automotive_Repair_C1/Engine_Fault_Codes_F29/ford_code_122_repair_P57992/

these are the instructions I followed from this thread

"Unplug the sensor with the key on and measure the voltage between the gray with red wire and the brown with white wire and you should have 5 volts.
If that is OK plug it back in and measure between the gray with red and the gray with white and you should have between .5v and .75v at idle. As you slowly open the throttle, the reading should slowly increase to just under 5v at Wide open throttle."

these are the same colors as my wires. the only major difference is that my voltage went up to 5.8 ish on the throttle test.

Also, this may be the problem, I will check it when I get off work. When I was testing the connection unplugged, I couldn't make contact with the brown wire white strip from the pin side of the plug, i had to probe it from the back with a paper clip, this could be the problem.

 

[unometooo]

I replaced the TPS and still no luck. When you make the repair and crank for this first time, it is the longest 4 or 5 seconds of your life and then the big, bad, ugly CEL comes on again. I have an idea that I have a short somewhere in the wiring harness that wraps around the engine 15 times. I will probably start pulling the harness apart this weekend and looking for a short.

 

[Maniak]

"Unplug the sensor with the key on and measure the voltage between the gray with red wire and the brown with white wire and you should have 5 volts.
If that is OK plug it back in and measure between the gray with red and the gray with white and you should have between .5v and .75v at idle. As you slowly open the throttle, the reading should slowly increase to just under 5v at Wide open throttle

It sounds like the Gray with red is your ground wire.. Easy to verify.. Put your volt meter between that and the battery.. When on the negative post you should see 0 volts and when on the positive battery post you should see 12v.

Assuming you get that then the brown/white wire is the 5v reference. That means when you test the TPS the gray/white will go from .8v up to the 5v reference voltage...

It sounds like you are seeing that So, my guess would be a break in the gray/white white as it runs around the engine..

~Mark

 

[unometooo]

It sounds like the Gray with red is your ground wire.. Easy to verify.. Put your volt meter between that and the battery.. When on the negative post you should see 0 volts and when on the positive battery post you should see 12v.

Assuming you get that then the brown/white wire is the 5v reference. That means when you test the TPS the gray/white will go from .8v up to the 5v reference voltage...

It sounds like you are seeing that So, my guess would be a break in the gray/white white as it runs around the engine..

~Mark

Only one of three wires should be a ground correct?

 

[Maniak]

Only one of three wires should be a ground correct?

Yes.. 1 ground, 1 5v reference and 1 signal...

~Mark

 

[unometooo]

Yes.. 1 ground, 1 5v reference and 1 signal...

~Mark

Ok, that helps. I was at my dads today and I didn't have my multimeter, all I had was a test light. I hooked the test light to the positive side of the battery and I touched the probe to all three wires in the connection and one of them lite the test light bright, one of them nothing and one of them lite the test light dim. The dim one must be shorting/grounding somewhere. I may pick up a new connector and try to bypass the whole harness, I just need to find the main connection on the harness. Its hard to follow the harness, it goes all over the place. Thanks for your help.

 

[unometooo]

FIXED......I was about to pull what hair I have left out when I decided to disconnect the engine harness under the alternator to help me eliminate grounds/shorts. The plug was pretty dirty so I cleaned it up with my carb/choke cleaner and kept looking for shorts. I connected everything back and pulled the codes again and the much desired 111 came up. I was like WTH and cranked the Explorer and no check engine light. I hate electrical problems, usually something super simple and after four days of hunting, you kick yourself in the butt when you find the problem. Mods, please add fixed to the title or "this guy got super lucky"