Service engine light on and codes P1122, P0122, 700 and 1100

Tiny
DANIELANDRITA
  • MEMBER
  • 1996 GMC SIERRA
  • 80,000 MILES
Service engine light comes on truck starts and idles, stalls when you try to accelerate, sometimes it restarts immediately, but sometimes it cranks but does not start. Some days it will let you make it down the block, but it always turns off. Have gotten codes from two different readers one gave code -p1122-p0122 made all test recommended TPS tested well replaced TPS prior to test, replaced harness, coil, module, tested fuel pressure tested 60 pounds with key on, 55-63 running. Tested fuel regulator, second reader gave code 700- 1100 but first codes did not show this time. Don't know if it matters but replaced transmission.
Sunday, April 28th, 2013 AT 4:23 PM

5 Replies

Tiny
CADIEMAN
  • MECHANIC
  • 3,544 POSTS
This positively could be a back flow problem. I would test for a partially or almost totally clogged catalytic converter. I'll give this some more thought. Thanks for using 2CarPros.
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Sunday, April 28th, 2013 AT 7:47 PM
Tiny
DANIELANDRITA
  • MEMBER
  • 3 POSTS
Because of mileage I was able to take vehicle to local dealer and have it checked thanks to a friend there. They checked and found that timing could be off. I was able to have a tech put it in time, but that didn't last long before it started again. I must say he commented that it was very troublesome. The one thing that has not been checked is EGR but the mechanic has told me that would not cause this problem. He also replaced temperature sensor.
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Sunday, April 28th, 2013 AT 8:13 PM
Tiny
CADIEMAN
  • MECHANIC
  • 3,544 POSTS
Have you tried starting fluid in the intake when it quits won't start?
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Sunday, April 28th, 2013 AT 8:54 PM
Tiny
DANIELANDRITA
  • MEMBER
  • 3 POSTS
Vehicle never fails to start. Sometimes I have to keep cranking it to get it to start, and it will eventually start. If I hold the accelerator down it starts, but as soon as I let go it turns off.
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Tuesday, April 30th, 2013 AT 12:10 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening,

The 122 is for the TPS circuit. You have not only the TPS but the throttle pedal sensor as well.

You need to test the throttle pedal sensor as well. If you have a scan tool that can read live data, I would watch the voltages on the al sensor. You have a 5 volt reference and signal voltage. The signal should go from 0 to 5 while pushing the pedal.

The 1122 is the same as the 122.

The 700 is for the transmission. It is a general code that means there are other codes stored in the transmission.

Roy

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides a voltage signal which changes relative to the throttle blade angle.

The TP sensor signal voltage varies from about 0.5 volts at idle to about 4.5 volts at Wide Open Throttle (WOT). The TP sensor signal is one of the most important inputs used by the Vehicle Control Module (VCM) for fuel control and for most of the VCM control outputs. Each time the voltage drops below 1.25 volts and stops, the VCM assumes this value as 0 throttle angle. The measures the percent throttle from this point on. The DTC is a type A DTC.

CONDITIONS FOR SETTING THE DTC
The following conditions will set the DTC:

Engine running.
TP sensor voltage is less than 0.15 volts.

ACTION TAKEN WHEN THE DTC SETS

Important: The scan tool will not indicate a default value.

The VCM sets the DTC P0122. The VCM turns on the Malfunction Indicator Lamp (MIL) when P0122 is reported, and 1 failure has occurred.

CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

DIAGNOSTIC AIDS
The scan tool reads throttle position in volts. The TP should read about 0.45 to 0.85 volts with the throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT).

An open or short to ground in the 5 volt reference circuit or the TP sensor signal circuit results in a DTC P0122. Refer to the Intermittents.

Scan the TP sensor signal while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from below 1.25 volts (1250 mV) when throttle was closed, to over 4.5 volts (4500 mV) when throttle is held at the Wide Open Throttle (WOT) position.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

2. If the TP signal measures less than 0.15 volt, then the fault exists.
3. This test simulates the DTC P0123 (high voltage). If the VCM recognizes the high signal voltage, the VCM and the wiring are okay.
4. This test simulates a high signal voltage in order to check for an open in the TP signal circuit.
6. This step checks the 5 volt reference circuit for an open, short to ground, or a poor connection, or a faulty VCM.
7. The VCM terminals GR 12 and GR 27 are spliced together inside the VCM. When checking the 5 volt reference for a short to ground, both the 5 volt reference circuits and all the components on the 5 volt reference circuits must also be checked.
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Friday, April 24th, 2020 AT 5:26 PM

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