PINPOINT TEST A: DTC B2266 OR B2267
Test Step
Result / Action to Take
A1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
Disconnect: HVAC Module C228a.
Disconnect: HVAC Module C228b.
Measure the resistance between HVAC module C228b-8, circuit 436 (RD/LG), harness side and
HVAC module C228a-20, circuit 438 (RD/WH), harness side.
Is the resistance greater than 500 ohms?
Yes
For DTC B2266
,GO to
A2
.
For DTC B2267
,GO to
A3
.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK, REPAIR circuits 436 (RD/LG) and 438 (RD/WH)
for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the
system for normal operation.
A2 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
Measure the
low-side
resistance between HVAC module C228b-4, circuit 437 (YE/LG), harness
side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
Measure the
high-side
resistance between HVAC module C228b-4, circuit 437 (YE/LG), harness
side and HVAC module C228b-8, circuit 436 (RD/LG), harness side.
Is the resistance between 250 and 5,500 ohms?
Yes
GO to
A4
.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK and:
If the
low-side
resistance only is greater than 5,500 ohms, REPAIR
circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the
low-side
resistance only is less than 250 ohms, REPAIR circuits
437 (YE/LG) and 438 (RD/WH) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the
high-side
resistance only is greater than 5,500 ohms, REPAIR
circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the
high-side
resistance only is less than 250 ohms, REPAIR circuits
437 (YE/LG) and 436 (RD/LG) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the
high-side and low-side
resistance is greater than 5,500 ohms,
REPAIR circuit 437 (YE/LG) for an open. CLEAR the DTCs. REPEAT
the self-test. TEST the system for normal operation.
A3 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
Measure the
low-side
resistance between HVAC module C228b-5, circuit 1122 (RD), harness
side and HVAC module C228a-20, circuit 438 (RD/WH), harness side.
Measure the
high-side
resistance between HVAC module C228b-5, circuit 1122 (RD), harness
side and HVAC module C228b-8, circuit 436 (RD/LG), harness side.
Yes
GO to
A4
.
No
CARRY OUT the Blend Door Actuator Component Test in this section. If
the actuator tests OK and:
If the
low-side
resistance only is greater than 5,500 ohms, REPAIR
circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the
low-side
resistance only is less than 250 ohms, REPAIR circuits
1122 (RD) and 438 (RD/WH) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the
high-side
resistance only is greater than 5,500 ohms, REPAIR
circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-
test. TEST the system for normal operation.
If the
high-side
resistance only is less than 250 ohms, REPAIR circuits
1122 (RD) and 436 (RD/LG) for a short together. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
If the
high-side and low-side
resistance is greater than 5,500 ohms,
REPAIR circuit 1122 (RD) for an open. CLEAR the DTCs. REPEAT the
self-test. TEST the system for normal operation.
Page 5 of 45
2006 Town Car Workshop Manual
12/30/2011
http://www.fordtechservice.dealerconnection.com/pubs/content/~WS6G/~MUS~LEN/19/...