P0643 Primary 5 volt circuit high. What does this mean?

[Chris Mallett]

This is what my Smarty is telling me. I am now having trans issues, and I have been scanning my truck all day, and this code is constant. I also have the p0107 and p0108 codes, but I THINK these are not major. I am also getting a P0483 fan speed code. The problems (today) have went from no lockup in tow/haul, to not finding 2nd gear at all. I even tried manual shifting. If someone knows what in the world is causing the P0643, Please let me know. TIA, Chris

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[Chris Mallett]

Anyone? I hate to toast a tranny over a small relay....

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[Chris Mallett]

Help??????

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[Chris Mallett]

I think (KNOW)I am having a wiring issue, Because at random times, the key will not send power to the ECM, and I have to get under the hood, unlpug and plug back in this harness...

Somebody help me, I hate not having a clue of what is going on...

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[Jusbecuz]

I have spent the last 30 minutes searching for this here, dtr, google, yahoo, and could find nothing other than what the code meant, sorry, so a bump to the top

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2003 3500 2WD, DRW, Quad Cab, Automatic 48RE, 3.73. stock HO. Dipricol Tranny, Boost, EGT Gauges
Jeff K. - ACDC

[Chris Mallett]

Thanks for the help, I cannot locate either...Another bump.

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[JWH_03_Dodge]

Here's P0643 out of the manual, I'd start there to eliminate the fan clutch assembly.

The K668 (5V supply) is on pin 5 of the 6 pin connector to the fan, check voltage there.

I've subscribed to the thread and check it a couple times today.


P0643-HIGH VOLTAGE AT THE #2 SENSOR SUPPLY CIRCUIT

For a complete wiring diagram Refer to Section 8W.

When Monitored:
With the key on.

Set Condition:
Voltage detected on the #2 sensor supply circuit was above a calibrated value.

Possible Causes
FAN CLUTCH ASSEMBLY
(K668) 5-VOLT SHORTED TO VOLTAGE
INTERMITTENT CONDITION
ECM


Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Diagnostic Test
1. FAN CLUTCH ASSEMBLY

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Disconnect the Fan clutch harness connector.

NOTE: Check connectors - Clean/repair as necessary.


With the scan tool, read DTCs.

Did P0483 set?

Yes
Replace the Fan clutch assembly.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

No
Go To 2



2. (K668) 5-VOLT SHORTED TO VOLTAGE

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Disconnect the ECM harness connectors.
Disconnect the Fan harness connector.

NOTE: Check connectors - Clean/repair as necessary.


Measure the voltage between the fan speed sensor (K668) 5-volt supply circuit and battery negative.

Is the voltage greater than 1 volt?

Yes
Repair the (K668) 5-volt supply shorted to voltage.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

No
Go To 3



3. ECM

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Turn the ignition off.
Reconnect the ECM harness connectors.
Turn the ignition on.
Measure the voltage between the (K668) 5-volt supply circuit in the sensor harness connector and battery negative.

Is the voltage greater than 6 volts?

Yes
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

No
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

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'03 2500, 4x4, 5sp, QCLB, 90hp injectors, Glacier Fuel System, Quad Race Box, 5" exhaust, still looking for my silencer ring and muffler

[JWH_03_Dodge]

Hey, back up here, I just checked the other codes you're getting, P0483 is the fan speed, so unplug that fan connector and see if the P0643 is still active..

The P0107 and P0108 contradict each other (inlet air pressure sensor voltage too low and high respectively), but both lead back to the ECM.

Try the fan connector, but i hate to say it, you might be looking at an ECM

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'03 2500, 4x4, 5sp, QCLB, 90hp injectors, Glacier Fuel System, Quad Race Box, 5" exhaust, still looking for my silencer ring and muffler

[Chris Mallett]

Thanks for the help, I will check that this evening. I drove the truck to work today, and the data plug/unplug is getting more frequent. I hope this is not an ECM problem.

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[JWH_03_Dodge]

no problem. if you get stuck, just ask, nothing going on tonight, so i'm here while we watch tv

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'03 2500, 4x4, 5sp, QCLB, 90hp injectors, Glacier Fuel System, Quad Race Box, 5" exhaust, still looking for my silencer ring and muffler

[Chris Mallett]

The plug problem is getting WAY worse...8 times to get it to work 15 minutes ago...

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2005 QC LB Dually, 4x4, F1 Helix 2 Cam, Sportsman springs, Fluidampnr, Edge Juice w/Attitude, Smarty, S&B Cold air intake, Needing tranny goodies badly.

Check out the West Virginia Cummins Crew

[JWH_03_Dodge]

have you tried unplugging the fan and seeing if it is isolated to that circuit?

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'03 2500, 4x4, 5sp, QCLB, 90hp injectors, Glacier Fuel System, Quad Race Box, 5" exhaust, still looking for my silencer ring and muffler