Working my way through fault codes, need help

[Sparky]

I just read somewhere that Ford put those holes in the throttle plates  in later years as some kind of "anti sludge" thing. I guess more air in the mixture prevents build up of contaminants?

[Sparky]

Here's a good post that discusses the "Sludge Resistant Throttle Body". Most of the info about it is towards the end.

https://www.fullsizebronco.com/threads/all-throttle-bodies-created-equal-gettin-myself-in-deeper.353786/

[vjsimone]

That's an interesting thread, brings back memories.
Did you read the TSB 892404 that was posted on that thread? I remember that one.

[Sparky]

I wasn't aware of that issue. Good to know for the future.

[Sparky]

Well, I thought I had these codes cleared but a couple have come back. In the process of troubleshooting I noticed that when I am verifying a good ground at a component like the TPS, when the key is on (engine off) I have high resistance to ground. Specifically, I am back probing the black (ground) wire on the TPS and checking resistance to the neg. battery post with the other lead. I had 114 ohms with KOEO but less than 1 ohm with the key off (reference and signal voltages were normal). Then I checked other grounding paths like from the ground stud next to the wiper motor back to the neg. battery post. With KOEO I had about 34 ohms, with key off I had less than 1 ohm. I also checked the same path with key on for voltage drop and got much less than 1V which tells me that it's not high resistance because of high current, otherwise it would be showing a voltage on the meter. Is this normal? Still learning about vehicle wiring systems so any help would be appreciated.

[Sparky]

OK, I thought more about this and it occurred to me that you are supposed to take resistance readings with the power off. I assume that having the key on would basically energize the circuit and throw off the meter readings. Does that sound right?

[Gary Lewis]

That may be the issue as your description was very confusing.  So maybe with the ignition of it'll make more sense.

[Sparky]

Sorry for the confusion. With the TPS I was just making sure I had a low resistance path from the signal return wire to battery ground per this youtube video (starts at :30):

https://www.youtube.com/watch?v=lJEGigONelc&t=138s

My mistake was I missed the part about leaving the ignition off.

The second situation was totally separate. I just wanted to check the resistance from the battery negative to the ground stud next to the wiper motor.