Throttle Control Position Sensor - 2021 6.0L

[Ferdischaefer]

Hey everyone, got the following issue:

can't rev up the engine at all. Stays on idle speed at 800rpms which is slightly higher than normal. Diacom shows the following fault codes, sometimes both of them, sometimes only one: SPN 91 TCP #1 Sensor Fault / FMI 3 TCP #1 Voltage High or / and SPN 91 TCP #1 Sensor Fault / FMI 16 TCP #1% higher than TCP #2%. The readings in Diacom say TCP1 voltage is 4.91, TCP 2 is 0.25 VDC.

All concerned items I can think of were replaced: throttle body, throttle control unit from Livorsi and ECM. Still getting the same though.

When doing a throttle test in Diacom it seems that TCP1 actual is always on 100% whilst TCP 2 actual changes according to the throttle position. Seems there is no communication between the throttle and the throttle body.

Anybody got any ideas where to start searching?

[Scooter G]

So you are not feeling ignored on your 1st post.
Do you have a Nautique Dealer in Doha, and where are you on your warranty?
You have access to a Diacom, which sounds like you have a working knowledge on systems.
You have Xtreme Marine there, a Supreme Dealer, but I see a bunch of Nautique pics on their FB page.
Not sure I have run across a similar problem, but if anyone has a clue, my poke would be jpwhit.
I have an older Diagnostic Manual but it does list your 91 Codes, and then cross references other DTC Codes.
Not sure if this will be of any help, but worth a shot (see page 209):
PCM Diagnostic Service Manual.pdf

[jpwhit]

Hey everyone, got the following issue:

can't rev up the engine at all. Stays on idle speed at 800rpms which is slightly higher than normal. Diacom shows the following fault codes, sometimes both of them, sometimes only one: SPN 91 TCP #1 Sensor Fault / FMI 3 TCP #1 Voltage High or / and SPN 91 TCP #1 Sensor Fault / FMI 16 TCP #1% higher than TCP #2%. The readings in Diacom say TCP1 voltage is 4.91, TCP 2 is 0.25 VDC.

All concerned items I can think of were replaced: throttle body, throttle control unit from Livorsi and ECM. Still getting the same though.

When doing a throttle test in Diacom it seems that TCP1 actual is always on 100% whilst TCP 2 actual changes according to the throttle position. Seems there is no communication between the throttle and the throttle body.

Anybody got any ideas where to start searching?

TCP 1 and 2 are two parts of a redundant sensor setup. They are setup with different resistance value potentiometers such that if wires get shorted together that TCP 1 won't look like TCP 2 or vice versa to the ECM. But the percentage calculations for TCP 1 and 2 have to be within a certain range for the sensor reading to be considered valid by the ECM.

So most likely cause is a wiring harness issue, since you've replaced all the related components. Either that or you got really unlucky with a new part that is defective.

I would debug by taking manual voltage reading at various points in the system with a meter and compare to what ECU is seeing via Diacom to locate the wiring fault.

[Ferdischaefer]

Thank you guys for your input. I started by checking all the connectors in the wiring harness and found one that looks slightly dirty... cleaned it and it turned out that was the issue. Glad it was such an easy fix in the end and I didn't had to check wire by wire. Also good learning experience to look at these connectors from time to time
Scooter G, the manual is great!

[Scooter G]

Good deal, way to go!
Makes me nervous that a '21/22 would have a dirty connection, but when it's 112 degrees and 110% of your surrounding landscape is sand, I could see how that is possible, lol.

That place just looks amazingly surreal over there, big money, I would love to crash one of those water huts on Banana Island. Where is your go to for most of your boat runs?

[Ferdischaefer]

Yeah, the conditions are pretty harsh out here. The water is very very salty as well and the dust find their way into everything. It's a pretty good place to wakesurf though. Bit hot in the summer but we can wakesurf all year round and water is usually really flat in the mornings. You seem to know the pace a little bit, preferred area is in this bay between west bay and the pearl