so here are the codes i got...p0475,p0478,p0470,p01211,p0476 and p1668.I only get the p1668 code if i start my truck shut it off and do a buzz test right away.I ran koeo and koer test about 5 times and i didnt get that code,i also ran the buzz test normally about 8 times and never got that code.so i dont no why i only get it if i run a buzz test right after i start mytruck.
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Some reading for you :

FJ1 DIAGNOSTIC TROUBLE CODE (DTC) P1670 and P1668
DTC P1668 and P1670 indicates that a communication error has occurred between the PCM and the IDM.
Possible causes:
Open fuse
IDM relay
Open or shorted IDM enable circuit
Open/short in EF circuit
Open/short in FDCS circuit
IDM powering circuits
PCM
Check for other codes.
Key on, engine off.
Perform KOEO On-Demand Self Test and retrieve Continuous DTCs.
Was DTC P1668 present?
Yes No
If DTC P1668 is present, GO to FJ2 . If DTCs P1667 and P1663 are set together with or without DTC P1668, GO to FJ6 .
If DTC P1298 is also present, REPLACE the IDM.

If DTC P1667 is also present, GO to KA1 .

If DTC P1663 is also present, GO to KF1 .

If DTC P1662 is also present, GO to NC1 .

If P1670 was set without any other DTC, GO to FJ10 .


FJ2 CHECK CIRCUIT 818 (GY/W) FOR OPEN
Install breakout box; leave PCM disconnected.
Disconnect the IDM harness connector.
Measure resistance on Circuit 818 (GY/W) between PCM Test Pin 48 and IDM harness connector Pin 4.
Is resistance less than 5 ohms?
Yes No
GO to FJ3 . REPAIR open in Circuit 818 (GY/W). RESTORE system. CLEAR DTCs and RETEST.

FJ3 CHECK CIRCUIT 818 (GY/W) FOR SHORT TO GROUND
Measure resistance between IDM relay Circuit 818 (GY/W) and battery ground.
Is resistance greater than 10,000 ohms?
Yes No
GO to FJ4 . REPAIR ground short in Circuit 818 (GY/W). RESTORE system. CLEAR DTCs and RETEST.

FJ4 CHECK CIRCUIT 818 (GY/W) FOR SHORT TO POWER
Key on, engine off.
Measure for voltage on Circuit 818 (GY/W) between PCM Test Pin 48 and battery ground.
Is voltage present?
Yes No
REPAIR short to power on Circuit 818 (GY/W). RESTORE system. CLEAR DTCs and RETEST. GO to FJ5 .

FJ5 CHECK SIGNAL RETURN CIRCUIT 359 (GY/R)
Turn ignition switch to OFF.
Measure resistance on Circuit 359 (GY/R) between PCM Test Pin 91 and IDM connector Pin 2.
Is resistance less than 5 ohms?
Yes No
GO to FJ6 . REPAIR open in signal return Circuit 359 (GY/R). RESTORE system. CLEAR DTCs and RETEST.

FJ6 CHECK IDM POWER
PCM connected, IDM disconnected.
Key on, engine off.
Measure voltage between IDM connector Pin 14 and battery ground.
Is B+ present?
Yes No
GO to FJ7 . GO to NC6 .

FJ7 CHECK IDM GROUND
Key off.
Measure resistance between IDM connector Pin 26 and battery ground.
Is resistance less than 5 ohms?
Yes No
GO to FJ8 . REPAIR open in IDM ground Circuit 574 (BK/PK). RESTORE system. CLEAR DTCs and RETEST.

FJ8 MEASURE FREQUENCY ON THE EF LINE
Connect PCM to breakout box.
IDM connected to harness.
Set up NGS Scan tool as follows:
Connect NGS Tester to the DLC
Connect test probe between NGS common and breakout box Pin 77 (ground).
Connect second test probe between NGS signal and breakout box Pin 48 (EF line).
Select VEHICLE and ENGINE
Select DIGITAL MEASUREMENT SYSTEM
Change level to 4 VOLT DC
Press the link button to choose a PID
Select PID/DATA MONITOR
Select RPM PID
Press START
Key on, engine running.
Measure frequency at 3 different RPMs.

rpm Frequency (Hz)
1000 66
2000 133
3000 200


For each rpm value, does the corresponding frequency match closely to the table?
Yes No
REPLACE PCM. RESTORE system. CLEAR DTCs and RETEST. REPLACE IDM. RESTORE system. CLEAR DTCs and RETEST.

FJ9 DIAGNOSTIC TROUBLE CODE (DTC) P1316 INDICATES THAT CODES ARE STORED IN THE IDM
Possible causes:
Injector(s) or circuit(s)
Open or shorted IDM enable circuit
Open/short in EF circuit
Open/short in FDCS circuit
IDM relay
IDM powering circuits
IDM
PCM
Check for other codes.
Key on, engine off.
Perform KOEO On-Demand Self Test.
Are IDM or any other codes stored?
Yes No
GO to the appropriate pinpoint test. GO to FJ10 .

FJ10 DTC P1316 OR P1670, CHECK FOR AN INTERMITTENT OPEN CIRCUIT
Key off.
Install breakout box, leave PCM disconnected.
Disconnect IDM.
Check for intermittent open in the following circuits:
Measure resistance on (FDCS) Circuit 821 (BR/O) between IDM connector Pin 17 and PCM Test Pin 95.
Measure resistance on (EF) Circuit 818 (GY/W) between IDM connector Pin 4 and PCM Test Pin 48.
Grasp the harness close to the IDM connector. Wiggle, shake the harness while working your way back to the PCM, while looking for a spike on the DVOM.
Do all readings remain below 5 ohms throughout procedure?
Yes No
GO to FJ11 . REPAIR open in the suspect circuit. RESTORE vehicle. CLEAR DTCs and RETEST.

FJ11 CHECK FOR AN INTERMITTENT SHORT TO GROUND
Check for intermittent short to ground on the following circuits:
Measure resistance on (FDCS) Circuit 821 (BR/O) between battery ground and PCM Test Pin 95.
Measure resistance on (EF) Circuit 818 (GY/W) between battery ground and PCM Test Pin 48.
Grasp the harness close to the IDM connector. Wiggle, shake the harness while working your way back to the PCM, while looking for a spike on the DVOM.
Do all readings remain above 10,000 ohms throughout procedure?
Yes No
GO to FJ12 . REPAIR short to ground on the suspect circuit. RESTORE vehicle. CLEAR DTCs and RETEST.

FJ12 CHECK FOR AN INTERMITTENT SHORT TO POWER
Key on, engine off.
Check for intermittent short to power on the following circuits:
Measure voltage on (FDCS) Circuit 821 (BR/O) between battery ground and PCM Test Pin 95.
Measure voltage on (EF) Circuit 818 (GY/W) between battery ground and PCM Test Pin 48.
Grasp the harness close to the IDM connector. Wiggle, shake the harness while working your way back to the PCM, while looking for a spike on the DVOM.
Did voltage ever appear on any circuit throughout procedure?
Yes No
REPAIR short to ground on the suspect circuit. RESTORE vehicle. CLEAR DTCs and RETEST. GO to FJ13 .

FJ13 VERIFY DTC P1316 AND/OR P1670
Restore vehicle.
Clear DTCs.
Cycle key off, than start engine.
Road test vehicle.
Perform KOEO On-Demand Self Test and retrieve Continuous DTCs.
Was DTC P1316 and/or P1670 set in Continuous without any codes in KOEO On-Demand?
Yes No
GO to FJ14 . REPAIR KOEO On-Demand DTCs. RESTORE vehicle. CLEAR DTCs and RETEST.

FJ14 ATTEMPT TO GENERATE IDM DTCS
Key off.
Disconnect one valve cover connector.
Start engine to generate IDM codes.
Perform KOEO Injector Electrical Self Test and KOEO On-Demand Self Test.
Are IDM codes retrieved?
Yes No
REPLACE PCM, RESTORE vehicle. CLEAR DTCs and RETEST. REPLACE IDM. RESTORE vehicle. CLEAR DTCs and RETEST.




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And a little more :

DTC P1211 indicates that injection control pressure was above or below commanded desired pressure during self test mode.
Possible causes:
incorrect oil or viscosity
poor oil quality
gel fuel/no fuel
low fuel pressure
damaged IPR valve
high-pressure oil system leak
damaged high-pressure oil pump
damaged PCM
Verify correct oil quality/viscosity and correct fuel grade are being used for the temperature conditions.
Is oil and fuel quality OK?
Yes No
GO to KE8 . REPAIR fuel or oil condition and VERIFY DTC does not return. RESTORE system. CLEAR DTCs and RETEST.

KE8 CHECK FUEL PRESSURE
Measure fuel pressure at regulator block.
Measure fuel pressure at idle and on road at WOT at full load. Fuel pressure at idle should be 138 kPa (20 psi) minimum, and 206-482 kPa (30-70 psi) at WOT full load.
Is fuel pressure OK?
Yes No
GO to KE9 . REPAIR fuel system concern. RESTORE system. CLEAR DTCs and RETEST.

KE9 CHECK OIL RESERVOIR LEVEL
Remove plug in top of oil reservoir and check level.
Is oil level within 25.4 mm (1 inch) of the top of the reservoir?
Yes No
GO to KE10 . REPAIR condition causing low oil supply to the reservoir. RESTORE system. CLEAR DTCs and RETEST.

KE10 ICP SENSOR CHECK
Key on, engine off.
Access ICP PID.
Is ICP reading 0 kPa (0 psi)?
Yes No
GO to KE11 . REPLACE faulty ICP sensor. RESTORE system. CLEAR DTCs and RETEST.

KE11 OIL AERATION CHECK
Accelerate engine to wide-open throttle and hold for three minutes.
Does ICP reading increase above 8618 kPa (1250 psi)?
Yes No
CHANGE engine oil and REPEAT test. RESTORE system. CLEAR DTCs and RETEST. GO to KE12 .

KE12 CHECK ICP WHILE PERFORMING SELF TEST
Note: During KOER On-Demand Self Test, ICP will be commanded high (17 MPa), then low (5 MPa) and then EBP will be commanded high and low.

Install ICP/EBP Adapter Cable D94T-50-A or equivalent between ICP sensor and engine harness.
Measure the voltage between ICP signal circuit and ground.
Perform KOER On-Demand Self Test.
Does voltage reading increase above 3 V and then decrease to approximately 1 V during the ICP portion of the KOER test?
Yes No
If DTC 1211 was displayed, REPLACE the PCM. RESTORE system. CLEAR DTCs and RETEST. GO to KE13 .

KE13 INJECTOR LEAK TEST
Disconnect high pressure hose from right cylinder head.
Using Oil High Pressure Leakage Adapter Set D94T-6600-A or equivalent, plug right high pressure hose.
Access IPR PID.
Start vehicle and record IPR reading.
Key off.
Reconnect right cylinder head high pressure hose.
Disconnect left cylinder head high pressure hose. Install adapter and ICP into high pressure hose.
Start vehicle and record IPR reading.
Are the two readings within 2% of each other?
Yes No
REPLACE faulty IPR valve. If DTC 1211 is still present, GO to KE14 . REPAIR internal oil leak on the bank with the higher IPR reading. REFER to the Powertrain Group in the Workshop Manual. RESTORE system. CLEAR DTCs and RETEST.

KE14 OIL SYSTEM PRESSURE TEST
Go to the Powertrain Group in the Workshop Manual. Perform pressurized oil leak checks.
Is a leak condition indicated?
Yes No
REPAIR leak as necessary. RESTORE system. CLEAR DTCs and RETEST. REPLACE high pressure oil pump. RESTORE system. CLEAR DTCs and RETEST.

KE15 CONTINUOUS DIAGNOSTIC TROUBLE CODE (DTC) P1211, P1209
DTC P1209 and P1211 indicates that injection control pressure was above or below desired level under normal driving conditions.
Possible causes:
incorrect oil or viscosity
poor oil quality
gel fuel/no fuel
low fuel pressure
damaged IPR valve
high-pressure oil system leak
damaged high-pressure oil pump
damaged PCM
Verify correct oil quality/viscosity and correct fuel grade are being used for the temperature conditions.
Is oil and fuel quality OK?
Yes No
GO to KE16 . REPAIR fuel or oil condition. RESTORE vehicle. CLEAR DTCs and RETEST.

KE16 RECHECK FUEL PRESSURE
Measure fuel pressure at regulator block.
Measure fuel pressure at idle and on road at WOT full load. Fuel pressure at idle should be 138 kPa (20 psi) minimum, and 206-482 kPa (30-70 psi) at WOT full load.
Is fuel pressure OK?
Yes No
GO to KE17 . REPAIR fuel system concern. RESTORE vehicle. CLEAR DTCs and RETEST.

KE17 PERFORM KOER ON-DEMAND SELF TEST
Perform KOER On-Demand Self Test.
Is DTC P1211 set?
Yes No
GO to KE9 . GO to KE18 .

KE18 CHECK OIL LEVEL IN RESERVOIR
Note: If may be necessary to soak vehicle if a leakdown concern is indicated.

Remove plug from top of oil reservoir and check level.
Is oil level within 25.4 mm (1 inch) of the top of the reservoir?
Yes No
GO to KE19 . REPAIR condition causing low oil supply to the reservoir. RESTORE system. CLEAR DTCs and RETEST.

KE19 CHECK ICP SENSOR
Key on, engine off.
Access ICP PID.
Is injection control pressure reading 0 kPa (0 psi)?
Yes No
GO to KE20 . REPLACE ICP sensor. RESTORE system. CLEAR DTCs and RETEST.

KE20 CHECK OIL AERATION
Accelerate engine and hold at 3300 rpm for three minutes.
Does injection control pressure reading increase above 8618 kPa (1250 psi)?
Yes No
CHANGE engine oil. RESTORE system. CLEAR DTCs and RETEST. GO to KE21 .

KE21 CHECK IPR DUTY CYCLE UNDER LOAD
Run vehicle at WOT and full load condition.
Does IPR duty increase to 65%?
Yes No
REPLACE IPR valve. RESTORE vehicle. CLEAR DTCs and RETEST. Unable to duplicate failure. RESTORE vehicle. CLEAR DTCs and RETEST.




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thanks for the info.the problem with the p1668 code is that i dont get it with either the koeo test or the koer test,only when i run a buzz test right after i shut the truck off.so im not shure what to do..

 

any body else have any insite?

 

bump to the top.

 

Caleb,

You are not alone.

I can drive my truck like I stole it or drive it like the old man I am and never get the P1668 code, but if I do a buzz test it sets the code. I just ignore it because the truck runs fine. If your truck is running fine don't let it concern you. Clear it and forget it.

 

i guess thats what im going to have to do.Because its never there when i pull codes,and its never there when i run test's.i dunno run her till she dies..

 

If it ain't broke don't fix it.

At least we both know it happens to someone else.

I'll make you a deal. If I ever find out why the 1668 sets after a buzz test I'll let you know and you do the same for me. At least post about it. I will.

 

sounds good will do.

 

Backatcha Later.