Pinpoint Test D: DTC B1259 Or DTC B1261 — Solar Radiation Sensor Open Circuit Or Short To Ground
Refer to Wiring Diagrams Cell
55
, Automatic Climate Control System for schematic and connector information.
Normal Operation
Under normal operation, the solar radiation sensor receives a ground through circuit 676 (PK/OG). A 5-volt reference voltage is supplied to the solar radiation sensor from the EATC module
through circuit 476 (BN/YE) (LH) and circuit 468 (BN) (RH).
Possible Causes
Is the resistance less than 5 ohms?
C4 CHECK CIRCUIT 3059 (YE/LG) FOR AN OPEN
Measure the resistance between EATC module C228b-16, circuit 3059 (YE/LG) and ambient
temperature sensor C132-2, circuit 3059 (YE/LG).
Is the resistance less than 5 ohms?
Yes
GO to
C7
.
No
REPAIR circuit 3059 (YE/LG) for an open. CLEAR the DTCs.
REPEAT the self-test. TEST the system for normal operation.
C5 CHECK CIRCUIT 3061 (LB/OG) FOR A SHORT TO CIRCUIT 3059 (YE/LG)
Ignition OFF.
Disconnect: EATC Module C228a.
Disconnect: EATC Module C228b.
Measure the resistance between ambient temperature sensor C132-1, circuit 3061 (LB/OG) and
C132-2, circuit 3059 (YE/LG).
Is the resistance greater than 10,000 ohms?
Yes
GO to
C6
.
No
REPAIR circuit 3061 (LB/OG) for a short to circuit 3059 (YE/LG).
CLEAR the DTCs. REPEAT the self-test. TEST the system for
normal operation.
C6 CHECK CIRCUIT 3061 (LB/OG) FOR A SHORT TO GROUND
Measure the resistance between EATC module C228-17, circuit 3061 (LB/OG) and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to
C7
.
No
REPAIR circuit 3061 (LB/OG) for a short to ground. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
C7 CHECK MODULE CONNECTION
Carry out the Electronic Automatic Temperature Control (EATC) Module Cold Boot Process.
Carry out the EATC on-demand self test.
Operate the system.
Does the concern return?
Yes
INSTALL a new EATC module. REFER to
Section 412-01
. TEST the
system for normal operation.
No
The system is operating correctly at this time. The concern may
have been caused by a loose or corroded connector. CLEAR the
DTCs. REPEAT the self-test. TEST the system for normal operation.
Page 12 of 45
2006 Town Car Workshop Manual
12/30/2011
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