Steered onto the pavement after a trail ride with the ORM back to OEM mode and received, as a parting gift, P0120 (TP- APP) throttle position switch /sensor and P1256 (unknown) Codes have not cleared after several normal driving sessions.

-I'll check the wiring to the TP/APP when I find it. Vehicle runs fine for now with the only other mod being the EMH.
-Guessing P1256 has something to do with Fuel & Air metering-injector circuit?
-Ever get these two error codes together?

Last week I cleared the Anti lock brake dash light by reseting/ burnishing and applying di-electric grease the front two wheel sensor electrical connectors, the rear axel tone ring sensor electrical connector and the main ABS controller connector. I would not think this would have anything to do with present codes unless P1256 has something to do with the brakes.

BTW...Harbor Frieght has had the $39.99 code readers back ordered for some time now. Ordered (1) 2 weeks ago. Should have went local.

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'05 Jeep Liberty CRD, '03 Dodge 2500 Cummins HO CRD 6spd, '91 GMC Topkick Caterpillar 3116 215hp MUI Diesel, '93 Volvo 240 Wagon, '06 Kubota Diesel Backhoe

P1256....any one know what gives??

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'05 Jeep Liberty CRD, '03 Dodge 2500 Cummins HO CRD 6spd, '91 GMC Topkick Caterpillar 3116 215hp MUI Diesel, '93 Volvo 240 Wagon, '06 Kubota Diesel Backhoe

That ties in with the fuel\air metering system - check your Boost hoses for ruptured - also check the air filter for dirty - while you're in there, check the MAF sensor for dirty - then time for a MAP sensor cleanup, intake manifold, 4-wire connector under the 3-wire Rail Pressure connector, towards the back

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'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I couldn't find that code in the service manual or any where else. I'll ask the service manager if they have that code on file and I'll post it in the tech section... Just assumed it was linked to the fuel/ air system in general as per the info from OBII.com. I do clean the sensor on a regular basis but I may have left off a connector when I went at the ABS controller connector?

Incidently, you do need to remove the battery tray to get at the ABS controller connector to get it to unlatch. Maybe time for an air filter as stated. (3) weeks now and still no Harbor Freight code reader but the dash read out displays them OK with the four ignition key on -off cycle method... just no ability to reset the codes instantly.

Much thanks for the response.

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'05 Jeep Liberty CRD, '03 Dodge 2500 Cummins HO CRD 6spd, '91 GMC Topkick Caterpillar 3116 215hp MUI Diesel, '93 Volvo 240 Wagon, '06 Kubota Diesel Backhoe

Autozone will scan it free - maybe the last two digits in those codes are reversed

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'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

I get a code occasionally for the throttle sensor... Takes a couple on-off cycles to clear. Do you use both feet to drive? I modulate the brake while on the accelerator and that sets it off. Computer thinks its a sticking throttle... at least thats what it says in the owners manual... right next to the part about not using both feet to drive... : P

Cheers,
Erik

I have caused a dash light to illuminate when riding the brake a little when engaging the throttle. That was when I wanted to hear the engine high idle when I was slowly making my way thru the jeep show parking lot That light cleared after a few re-starts. I read the P1256 code with the dash display so I'll take it to the Zone for a read to see if it's reversed.

The ABS and brake lights still come on when they want so I'll see if it threw a code for one of the wheel sensors when I get to the Zone or use my code reader ... if and when it comes I think I understand why there is such a back order lead time on the darn Harbor Freight code reader. Everybody is trying to keep running what they've got I guess.

Can the wheel speed sensors be dirty enough to cause them to malfunction or do they just usually fail?

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'05 Jeep Liberty CRD, '03 Dodge 2500 Cummins HO CRD 6spd, '91 GMC Topkick Caterpillar 3116 215hp MUI Diesel, '93 Volvo 240 Wagon, '06 Kubota Diesel Backhoe

Because the TurboDiesel is capable of so much more torque, ECM apparently has been programmed to monitor APP and ABS input, such that when brake is modulated under initial accel, ECM pulls power until condition is corrected - mine loses all throttle response for ~10secs until I quit playing twinkle toes on the accel\brake pedals - scary the first few times it occurs, but I've slowly learned to place the ole left foot firmly on the floorboard, at a safe distance from the brake pedal until such time as required for some necessary impedance, and the right foot is safely off the accel pedal - never any DTC's, tho

Usually you can just unplug\replug the WSS harness connectors to correct the problem, but tonewheels have been known to crud up from excess off-roading, requiring cleaning - just be careful, as the sensors can rust inplace in their respective bores, making for very difficult in removal

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'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go