Novak Conversions Jeep Wrangler TJ radiator

I’m losing my mind with this TPS!

Christian.mers

Point A to Point B
Original poster
Supporting Member
Joined
May 7, 2024
Messages
339
Location
Huntington, West Virginia
Just for reference, I have a 97’ with the 2.5l. I recently got a P0121 and P0123 DTC. Some symptoms that I have noticed that could point to my TPS is at once I let off my throttle my idle drops to about 200-300 RPM and oil pressure drops to 23-25psi. The oil pressure makes sense because the pump is barely moving anything at that low of an RPM. When idle drops it occasionally levels out at about 700rpm when coming to a complete stop (this is only an issue in stop and go traffic).

I tried everything that I can think of I backprobed the wires in here are my findings. Attached is my wiring diagram and I will be referencing the wire colors and tracer colors just for simplicity.

K7 200R is my 5v (Solid Orange)
K167 20 BR/YL is sensor Ground
K22 180 R/DB is my Signal wire (I’m not sure where the Red comes from but it’s Orange with a Blue Tracer)

Some confusion that may arise may be because my wires aren’t the same color as the Manual states….

All testing was done KOEO (Key On Engine Off) with ground directly to the battery backprobing with the TPS connector attached and DC V on my multimeter.

K7 which is supposed to be my 5V constant is resting at 0.768v and steadily increases to just under 4v at WOT

K167 which should be my ground is a 5.13v Constant

K22 which should be my signal wire is 10.4mV

Wtf is going on???? Maybe someone rewired my connector to be messed up but that wouldn’t explain the engine running perfectly fine 80% of the time and only having intermittent issues. I can wiggle the connector and TPS % fluctuates on my OBD2 scanner.

TPS% (Absolute Throttle Position) moves around from 23.5 to 23.9 to 24.3 approximately every 3 seconds with no throttle applied and eventually drops to 15.0-19.0 after applying throttle and fully releasing my foot.

Intake Manifold Absolute Pressure (the only map spec I can monitor) is steady at 9 (inHG)

TPS WOT sweep maxes out at 79.6 % on my scan tool and at WOT it fluctuates between 78.0, 78.4, 78.8, 79.6 but it usually maintains at 78.0% at WOT KOEO. It steadily increases in voltage when I use my multimeter to monitor.

I can’t monitor the throttle plate while fully pressing down the petal, but I zip tied my petal so it’s at WOT and the throttle plate is fully opened, my thought was maybe slack in the DBC wires. After that test and the Jeep sitting at KOEO for about 10 minutes. The TPS percentage has dropped to a steady 15.3.

I’m so scattered brained right now and I've been on this for like 4 hours so if anyone has knowledge that may help I’d appreciate it!







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I didn’t check the connectors or anything for corrosion, but unfortunately, this is my daily driver so I don’t know how feasible it is to send out my PCM at this current point in time.

Would it be worth it to test continuity through that entire wire from the PCM to the signal wire on the TPS I would not reveal anything I haven’t already determined?
 
Short to ground or faulty ground on the vehicle itself?

Usually faulty grounds due to time and corrosion.

Yep, that's my guess. When nothing in the circuit makes sense and it seems to be violating the laws of physics, its a ground problem. Power down, disconnect, and check things with an ohmmeter would be my next step.
 
Am I supposed to check resistance between the battery and the ground and look for anything above a certain ohm level?? What’s the fix if it’s a bad ground?

A bad ground can be either be caused by a loose connection, dirty connection or frayed ground wire....
You will need look at the wiring schematic and test continuity between the TPS connector and the Splice connections at S127, S133 and A4.
IF continuity is good; then wiggle the wires to see if the continuity changes dramatically.
You can use DeoxIT D5 electrical contact cleaner to assist with cleaning connector terminals.
DISCONNECT the battery before spraying contact cleaner on terminals that have voltage.
 
I've noticed my OBDII scantool plus the torque app gives inaccurate tps readings like 11% at closed to ~80% at wide open on my 2004 4.0L, but HP Tuners VCM Scanner is always accurate from 0 to 100%. Others have had a similar experience with torque showing inaccurate TPS position and I believe it is something with the torque app not interpreting the signal correctly.

You're looking for 0 ohms from the pin at the tps connector to the designated connector pin on the harness even if you jostle the wire. It sounds like there might be an issue on the 5V supply from your comment above.

You also want to make sure you don't see any current between the 5V supply or signal to ground or each other when jostling the wires.

If you do see issues with any of the above, you'll need to unwrap the harness back from the TPS plug to the harness and keep working back looking for the fault.

And then for the sensor itself check it's function by reading resistance between the 5V supply and signal at 0% throttle and 100% throttle opened by hand. It should drop and hold steady. And if you used a zip tie to hold the throttle steady partially open the resistance shouldn't fluctuate. I don't know what the spec is for throttle closed or wide open resistance, but they shouldn't be fluctuating.

There's also the engine to body ground on the firewall passenger side and body to battery ground to check which can be loose or corroded causing general random mayhem.
 
Also the factory orange no stripe wire coating often looks quite red to me irl and cameras have trouble discerning red/orange sometimes.

I'm not sure whether there's been any prior work done to your harness, but it looks factory wrapped.

Coincidentally this recent thread has the expected voltage ranges for the sensor, but on the later 05 model.
https://wranglertjforum.com/threads/ngc3-tps-help.86021/
 
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So I have not tested spices yet, but I tested straight from the PCM on A4 (Ground), A17 (5V Ref), and A23 (Signal wire)

A4- 1.1-0.8 OHMs
A17: 0.0-0.2 OHMs
A23: 1.9-2.1 OHMs but dropped to 1.3-1.5 OHMs after about 30 seconds of sitting connected

I saw no changes in resistance when wiggling the wires, but then again the resistance isn’t staying steady, so I’m getting a bounce of a few numbers in between the ranges listed above. I have the negative terminal on the battery disconnected as well as the PCM connector unplugged and I’m probing from the inside and then I’m back probing the TPS with the corresponding wire.

For Voltage (measured yesterday but just a recap)
K7 (or A17) which is supposed to be my 5V constant is resting at 0.768v and steadily increases to just under 4v at WOT

K167 (or A4) which is my ground is a 5.13v Constant reading with no fluctuations

K22 (or A23) which is my Signal wire remains steady at is 10.4mV with no fluctuations
 
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I just reconnected my battery and took another Voltage test with the key on and the engine off.

WITH MAP CONNECTED
At my red wire (5V Supply): 5.13V
At my R/DB Wires (TPS Signal): 0.764V Idle and 3.9V WOT
At my BR/YL Wire (Ground): 9.2mV

WITH MAP DISCONNECTED
At my red wire (5V Supply): 5.14V
At my R/DB Wires (TPS Signal): 0.768V Idle and 3.9V WOT
At my BR/YL Wire (Ground): 8.4mV
 
I just reconnected my battery and took another Voltage test with the key on and the engine off.

WITH MAP CONNECTED
At my red wire (5V Supply): 5.13V
At my R/DB Wires (TPS Signal): 0.764V Idle and 3.9V WOT
At my BR/YL Wire (Ground): 9.2mV

WITH MAP DISCONNECTED
At my red wire (5V Supply): 5.14V
At my R/DB Wires (TPS Signal): 0.768V Idle and 3.9V WOT
At my BR/YL Wire (Ground): 8.4mV

No significant change...
Looking at the wiring schematic; i thought this would be a problem area to test and rule out.
I would test the splice connections that I referenced earlier.
 
I’ve tested all of the wiring diagrams for the TPS from the PCM to the splices to the TPS and I’m getting the same or similar results. I sprayed a whole crap ton of Throttle body cleaner in my IAC and let it die out, then restarted the engine and did the same thing and I cleared the codes and I’ve driven it all day and no codes popped back up and the issues all seemingly disappeared.

I don’t understand at all….
 
I’ve tested all of the wiring diagrams for the TPS from the PCM to the splices to the TPS and I’m getting the same or similar results. I sprayed a whole crap ton of Throttle body cleaner in my IAC and let it die out, then restarted the engine and did the same thing and I cleared the codes and I’ve driven it all day and no codes popped back up and the issues all seemingly disappeared.

I don’t understand at all….

It sounds as though you cured a sticking IAC solenoid.
 
Novak Conversions Jeep Wrangler TJ radiator