Irregularly TPS voltage. new timbo installed

[99cummins5spd]

Hello all,

 

recently had a low voltage code p0122 on my 99. Figured it was the stock tps and decided to replace with the highly reviewed TIMBO. 

 

now I’m not sure if these issues were present before the timbo install due to not having a good code reader. I am now using a snap on brick code reader. 
 

my issue is with the key on, ignition off I have a steady tps voltage of .66 and it will rise appropriately with pedal push and return to .66. However when I start the truck and let it idle the voltage is very sporadic. Never staying at a solid number even when pushing the pedal. The truck runs and drives fine without one issue beside the check engine light. 
 

Anyone have any ideas? I uploaded a very short video due to size limits 

[99cummins5spd]

So I actually probed the actual sensor and I’m getting a steady .73 volts at idle. 
 

therefore I’m guessing it’s a wire or the ecm/pcm reading incorrectly 

 

Any input ?

[Great work!]

These trucks are prone to electrical noise and interference due to wiring  layout and design mistakes. First re terminate the battery terminal connections they need to be clean and tight. All the ground connections on the cab and engine need checked. Measure for AC voltage from the alternator or get it checked. Consider doing th WT ground mod search for WT ground mod.

[99cummins5spd]

1 hour ago, Great work! said:

These trucks are prone to electrical noise and interference due to wiring  layout and design mistakes. First re terminate the battery terminal connections they need to be clean and tight. All the ground connections on the cab and engine need checked. Measure for AC voltage from the alternator or get it checked. Consider doing th WT ground mod search for WT ground mod.

I appreciate your response. I cleaned the 3 pcm and 1 ecm connections thoroughly and added some dielectric grease to them. It seems to have solved it...for now.. I have all new battery terminals that I keep clean and greased. I may end up replacing all cables as well. 
 

I’ll do as you suggested with alternator and ground mod. Thank you!!

[dripley]

The other ends of the cables are just as important, not just the battery terminals. Your PCM and ECM are not case grounded. They have their own ground wires. The WT's ground mod covers it in depth and an easy mod the do. One the best mods I have done to my truck.

[Doubletrouble]

 I agree with @dripley, I've done the WT ground mod. After seeing for myself how these wires were spliced together by the factory it kinda made me sick. These trucks were not cheap when new nor are the newest 2021's and to see how they assemble some things is terrible.

 If nothing else and for no other reason do the WT mod just for piece of mind knowing it's done right.

Just my $.02

[Mopar1973Man]

W-T ground mod done here and kept my cruise control smooth now. I'm also Timbo's APPS user but when the AC noise got bad it will accelerate up to 75 MPH on its own the coast down to 55 or so and start over randomly. This with fly by cruise control. After the W-T mod no longer even an idea of it happening for over 2 years now. 

Edited December 21, 2020 by Mopar1973Man