DTC Troubleshooting: P0641
DTC P0641: Sensor Reference Voltage A Malfunction
NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description
Confirmed DTC
Pending DTC
P0641 Sensor Reference Voltage A Malfunction
    

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
P0641 Sensor Reference Voltage A Malfunction
    

Is DTC P0641 indicated?

     
YES
     
     
     
The failure is duplicated. Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the PCM and these parts. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot.?
CKP sensor
MAP sensor
Output shaft (countershaft) speed sensor (M/T)
Throttle body
APP sensor
2.
Determine possible failure area (VCC lines, others):

Determine possible failure area (VCC lines, others)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the following connectors.
CKP sensor 3P connector
MAP sensor 3P connector
Output shaft (countershaft) speed sensor 3P connector (M/T)
Throttle body 6P connector
APP sensor 6P connector

?3.
Turn the vehicle to the ON mode.

?4.
Clear the DTC with the HDS.


?5.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
P0641 Sensor Reference Voltage A Malfunction
    

Is DTC P0641 indicated?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Go to step 3.
3.
Shorted part check:

Shorted part check
?1.
Check for Pending or Confirmed DTCs with the HDS while reconnecting these parts, one at a time:
CKP sensor
MAP sensor
Output shaft (countershaft) speed sensor (M/T)
Throttle body
APP sensor

DTC Description
Confirmed DTC
Pending DTC
P0641 Sensor Reference Voltage A Malfunction
    

Is DTC P0641 indicated?

     
YES
     
     
     
Replace the part that caused the DTC when it was reconnected.?
     
NO
     
     
     
Check for poor connections or loose terminals at the PCM and the following parts, then go to step 1.
CKP sensor
MAP sensor
Output shaft (countershaft) speed sensor (M/T)
Throttle body
APP sensor
4.
Shorted wire check (VCC lines to ground):

Shorted wire check (VCC lines to ground)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Jump the SCS line with the HDS, and wait more than 1 minute.


?3.
Disconnect the following connectors.
PCM connector A (50P)
PCM connector E (80P)

?4.
Check for continuity between these test points and body ground individually.
Test condition
Vehicle OFF (LOCK) mode
CKP sensor 3P connector: disconnected
MAP sensor 3P connector: disconnected
Output shaft (countershaft) speed sensor 3P connector (M/T): disconnected
Throttle body 6P connector: disconnected
APP sensor 6P connector: disconnected
PCM connector A (50P): disconnected
PCM connector E (80P): disconnected

Connector
Terminal
PCM connector A (50P)
No. 45
PCM connector E (80P)
No. 70 and No. 75

Is there continuity?

     
YES
     
     
     
Repair a short to ground in the VCC wire(s) between the PCM (A45, E70, E75) and each part that was disconnected in step 2.?
     
NO
     
     
     
Go to step 5.
5.
Shorted wire check (VCC lines to power):

Shorted wire check (VCC lines to power)
?1.
Turn the vehicle to the ON mode.

?2.
Measure the voltage between these test points and body ground individually.
Test condition
Vehicle ON mode
CKP sensor 3P connector: disconnected
MAP sensor 3P connector: disconnected
Output shaft (countershaft) speed sensor 3P connector (M/T): disconnected
Throttle body 6P connector: disconnected
APP sensor 6P connector: disconnected
PCM connector A (50P): disconnected
PCM connector E (80P): disconnected

Connector
Terminal
PCM connector A (50P)
No. 45
PCM connector E (80P)
No. 70 and No. 75

Is there any voltage?

     
YES
     
     
     
Repair a short to power in the VCC wire(s) between the PCM (A45, E70, E75) and each part that was disconnected in step 2.?
     
NO
     
     
     
The VCC wires are OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM, then recheck. If DTC P0641 goes away and the PCM was substituted, replace the original PCM.?