Circ Pump Control Shorted - Mercedes-Benz Sprinter 2003 Manual

CABIN HEATER
Symptom:

CIRC PUMP CONTROL SHORTED

CIRCULATION PUMP RELAY
CIRCULATION PUMP RELAY HIGH SIDE CONTROL CIRCUIT SHORTED TO GROUND
PUMP RELAY HIGH SIDE CONTROL CKT SHORTED TO PUMP RELAY GROUND CKT
CABIN HEATER CONTROL UNIT
TEST
1 WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA
THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS
VENT THE EXHAUST WHEN OPERATING THE HEATER. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY
OR DEATH.
CAUTION: DO NOT PERFORM THIS TEST UNLESS DIRECTED HERE BY
THE HEATER PRE-TEST. ALWAYS PERFORM THE HEATER PRE-TEST
PRIOR TO PERFORMING ANY OTHER TEST FOR THE RESULT TO BE
VALID.
Turn the ignition off.
Install a substitute relay in place of the Circulation Pump Relay.
Turn the ignition on.
Verify that the Cabin Heater is switched off.
Set the blend control to the max heat position and the mode control to the floor
position.
With the DRBIII , erase the Cabin Heater Module's DTCs.
Start the engine. Allow the engine to idle.
With the DRBIII, monitor for Cabin Heater Module DTCs while performing the
following step.
NOTE: Do not disconnect the vehicle's battery or the heater's main power
supply while the heater is in operation or in run-down mode. Failure to
follow these instructions can result in excess emissions from the heater
during heater operation.
Switch the Cabin Heater on. If necessary, allow the heater to run through at least one
cycle of operation (approximately 10 minutes), and then switch the heater off.
Turn the engine off.
Does the DRBIII display: CIRC PUMP CONTROL SHORTED?
Yes → Go To 2
No
POSSIBLE CAUSES
ACTION
→ Replace the original Circulation Pump Relay in accordance with
the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
74
APPLICABILITY
All