LB7: Ficm problems???

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Mar 1, 2013
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Des Moines, Iowa
I had to replace the o-ring on the pipe to the heater core. When I was putting the new o-ring on, it shorted out with the terminal on the back of the alternator. I didn't think anything about it and when and started the truck and drove it around the block. It was the first drive I had in the truck after the engine was put in, and was having problems with throttle response. It had to have the pedal at 50% before it was start to rev. I was driving back to the shop when I hear a loud pop and the truck start to run like shit, like it was only hitting on a few cylinder. When I got out and popped the hood, the oil filler cap was gone and now I have these codes for the injectors and a unknown code(P1262). I don't know if the electrical shock screwed up the injectors or FICM. I hope I don't have rebuild my engine again.:mad: The truck will still run but like shit.
 

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MAXX IT OUT

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Mar 1, 2013
1,774
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Des Moines, Iowa
Ya, still can't find it. I going to do a compression check, I hope that I never cracked another piston. I don't know why it would of blow it off, it never did it before.:eek:
 
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Mar 1, 2013
1,774
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Des Moines, Iowa
I have done some research on p1262 and have a 10 page paper on what all could be the problem and how to find out what itand fix it, put has anyone else his problem?:confused:
 
quinton

quinton

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Nov 28, 2011
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Same thing kinda happened to my buddy. He was racing and he heard a pop and ran like crap afterwards. We've done everything I can think of and what the dealership has thought of. It's on a lly. Did injector harness fix, replaced all harness's, replaced 4 injectors that showed bad balance rates, replaced the FICM. Still nothing. It only runs like crisp every now and then though now. Sometimes it runs fine other times other times it runs like crap. It gives the injector harness codes. Only thing left that we can think of is replace the whole wiring harness for the engine. Thinking a wire somewhere shorted out or something.
 
redws6rocket

redws6rocket

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DTC P1262
Circuit DescriptionThe fuel injection control module (FICM) supplies high voltage to each fuel injector on the ignition voltage circuits. The FICM energizes each fuel injector by grounding the command circuit between the FICM and the fuel injector. The FICM monitors the status of the ignition voltage circuits and the fuel injector command circuits. When a fuel injector circuit condition is detected by the FICM, all of the fuel injectors on the affected ignition voltage circuit will be disabled. If a circuit condition is detected on a fuel injector circuit for cylinders 1, 4, 6, or 7, DTCs P0201, P0204, P0206, P0207 will set, along with DTC P1261. If a circuit condition is detected on a fuel injector circuit for cylinders 2, 3, 5, or 8, DTCs  P0202, P0203, P0205, P0208 will set, along with DTC P1262.

Conditions for Running the DTC•The ignition is ON.
•DTC U1800, or U2104 are not set.
Conditions for Setting the DTCThe ECM detects a circuit fault related to the high voltage circuit to cylinders 2, 3, 5, and 8.

Action Taken When the DTC Sets•The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
•The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
Conditions for Clearing the MIL/DTC•The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
•A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
•A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
•Clear the MIL and the DTC with a scan tool.
Test DescriptionThe number below refers to the step number on the diagnostic table.

2.This step determines if a wiring or injector problem caused this DTC to set. If DTC P1262 sets alone, an internal FICM fault is the cause.
DTC P1262 Step
Action
Yes
No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1
Did you perform the Diagnostic System Check–Engine Controls?
Go to Step 2
Go to Diagnostic System Check - Engine Controls

2
Is DTCs P0202, P0203, P0205, or P0208 also set?
Go to DTC P0201, P0202, P0203, P0204, P0205, P0206, P0207, or P0208
Go to Step 3

3
Replace the FICM. Refer to Fuel Injector Control Module Replacement.

Did you complete the replacement?
Go to Step 4
—

4
 1. Clear the DTCs with a scan tool.
 2. Turn OFF the ignition for 30 seconds.
 3. Start the engine.
 4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
Go to Step 2
Go to Step 5

5
Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?
Go to Diagnostic Trouble Code (DTC) List
System OK
 
Evan@InglewoodTrans

Evan@InglewoodTrans

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Aug 5, 2010
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quinton said:
Same thing kinda happened to my buddy. He was racing and he heard a pop and ran like crap afterwards. We've done everything I can think of and what the dealership has thought of. It's on a lly. Did injector harness fix, replaced all harness's, replaced 4 injectors that showed bad balance rates, replaced the FICM. Still nothing. It only runs like crisp every now and then though now. Sometimes it runs fine other times other times it runs like crap. It gives the injector harness codes. Only thing left that we can think of is replace the whole wiring harness for the engine. Thinking a wire somewhere shorted out or something.
Click to expand...

Aside from the pop we have a lly doing the same thing.
 
J

jkholder09

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Jan 8, 2012
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The alternator could have found a ground throgh the ficm or an injector.
Maybe try unplugging the 4 injectors listed and see if any test for a shorted coil or short to ground. before replacing the ficm
 
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Mar 1, 2013
1,774
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Des Moines, Iowa
So unplug the four injector harness and see if the codes keep up? If so then would it be the FICM. As for a FICM, any only on a LB7 should work on any other LB7 right and what is one worth.
 
J

jkholder09

New member
Jan 8, 2012
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Just check the injectors for a short to ground and see if you come up with anything.
If not swap a ficm. IIRC lly or lb7 will both work
 
quinton

quinton

Active member
Nov 28, 2011
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Granbury Tx.
Any ideas on what I got going? We've replaced everything that we can think of. FICM, injectors, injextor harness's only thing left we can think of is wiring. Any ideas?
 
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