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DirectInjection, Mechanic
Category: Heavy Equipment
Satisfied Customers: 95
Experience:  14 years experience. Certified Mercedes-Benz, Ford, Caterpillar, Allison Transmissions, Freightliner
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Got this code 128 230 06 TPS Idle Validation Switch Short to

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Got this code 128 230 06 TPS Idle Validation Switch Short to Ground, change the switch didn't help what's next
Hello. I believe I can help you here. First off by changing the switch you mean you changed the entire throttle pedal assembly, correct?
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Customer: replied 3 years ago.

No just switch that attach to pedal, the code reefers to TP Sensor Idle Validation Switch.

Should I try to change hole assembly?

Can you give me the last 6 of the VIN#?

Yes you normally have to replace the entire pedal assembly. The idle validation circuit actually consist of two switches. One is built into the pedal assembly it's self.
Customer: replied 3 years ago.

W04326 I inspected the pedal it looks good, it does turn the switch. My truck just idles, and ones I push the pedal it throws the code.

Okay just give me a couple minutes to look up your particular wiring schematic with your VIN#.
Customer: replied 3 years ago.

No problem

Was the new sensor you installed Part# XXXXX 131973? That is the particular one your truck calls for. Unfortunately you need to be able to see what we call "TPS Counts" in order to trouble shoot the problem which requires a laptop and diagnostic software. How ever there are a few things you can do to attempt to fix the issue. You should 3 wires at the throttle pedal sensor. D952, D916, and D417. These go to the firewall wall connector and into the engine compartment. D952 goes to pin #18 on the firewall connector. D916 goes to pin #8 on same conn. D417 goes to pin #9 on same conn. Once you get in the engine compartment these wires go from the same connector (engine compartment side) down to the engine ECM. D952 goes from the firewall connector pin #18 to Engine ECM connector pin #G1 D916 goes from pin #8 of the firewall connector to engine ECM connector pin #A3 D417 goes from firewall connector pin #9 to engine ECM connector pin #D2 There are two engine ECM connectors. The one you need to disconnect is the rear most one that is closest to the cab of the truck. I would use a multi meter and ohm out these wires from pin to pin and see if any of them are broken or if any of them are showing to be ground while both the engine ecm connector and the throttle pedal is disconnected. If one is found broken or showing ground to the truck even though everything is disconnected then you need to replace or repair that particular wire. If all wiring shows to be good and you are sure it is not a defective new TPS sensor then the only thing left is a bad engine ECM throwing a false code.



Customer: replied 3 years ago.

The new sensor par t# XXXXX XXXXX is it good?

Does my truck have another sensor pedal assy.?

Does it make any sense to change throttle pedal before troubleshooting?

That is the part number shown for your truck. It is likely that the part number now superceeds to another part#. Any parts person at any freightliner dealership if you call them can run that part # XXXXX gave you and tell you if it is the newest one or not. The one I gave you is the correct one tho. We just need to make sure you were sold the right sensor. I would just verify you received the correct part before check the wires.
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