DTC B048D or B048E
Diagnostic Instructions
DTC Descriptors
DTC B048D 01: Auxiliary Heater Temperature
Command Circuit Short to Battery |
DTC B048D 06: Auxiliary Heater Temperature
Command Circuit Low Voltage/Open |
DTC B048E 00: Auxiliary Heater System
Malfunction |
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Electrical Auxiliary Heater Control
|
B048D 06
|
B048D 06
|
B048D 01
|
-
|
Electrical Auxiliary Heater Signal
|
B048E 00
|
B048E 00
|
B048E 00
|
-
|
|
|
Circuit/System Description
The HVAC control module sends a pulse width modulation (PWM)
signal to the electrical auxiliary heater, if the interior
temperature is too low and additional heat is requested. The
request signal from the HVAC control module, battery positive,
ignition and ground circuits enable the electrical auxiliary heater
to operate. Through the signal circuit the electrical auxiliary
heater sends via a PWM signal the current status to the HVAC
control module.
Conditions for Running the DTC
• |
The HVAC control module is
ON. |
• |
The electrical auxiliary
heater is ON. |
Conditions for Setting the DTC
B048D 01
The voltage at the HVAC control module output to the electrical
auxiliary heater is always high.
B048D 06
The voltage at the HVAC control module output to the electrical
auxiliary heater is always low or floating.
B048E 00
The feedback signal of the electrical auxiliary heater does not
correspond with the requested PWM signal.
Action Taken When the DTC Sets
The electrical auxiliary heater is inoperative.
Conditions for Clearing the DTC
The feedback signal of the electrical auxiliary heater
corresponds with the requested PWM signal.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Manual HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. |
Verify that DTC B048D 01 or
B048D 06 is not set. |
⇒ If DTC B048D is
set
Refer to Electrical Auxiliary Heater
Control Circuit Malfunction. ⇓
If DTC B048D is not set
2. |
Verify that DTC B048E 00 is
not set. |
⇒ If DTC B048E is
set
Refer to Electrical Auxiliary Heater
Signal Circuit Malfunction. ⇓
If DTC B048E is not set
Circuit/System Testing
Electrical Auxiliary Heater Control Circuit Malfunction
1. |
Ignition OFF, disconnect the
X2 harness connector at the K33 HVAC Control Module and the X1
harness connector at the E40 Electrical Auxiliary Heater, ignition
ON. |
2. |
Verify that a test lamp
illuminates between the ignition circuit terminal 2 X1 at the E40
Electrical Auxiliary Heater harness connector and ground.
|
⇒ If the test lamp
does not illuminate and the circuit fuse is good
|
2.2 |
Test for less than 2 Ω
in the ignition circuit end to end. |
⇒ |
If 2 Ω or greater, repair the open/high resistance in the
circuit. |
⇒ |
If less than 2 Ω, verify the fuse is not open and there
is voltage at the fuse. |
⇒ If the test lamp
does not illuminate and the circuit fuse is open
|
2.2 |
Test for infinite resistance
between the ignition circuit and ground. |
⇒ |
If less than infinite resistance, repair the short to ground on
the circuit. |
⇒ |
If infinite resistance, replace the E40 Electrical Auxiliary
Heater. |
⇓ If the test lamp
illuminates
3. |
Test for less than 0.3 V
between the control circuit terminal 7 X2 at the K33 HVAC Control
Module harness connector and ground. |
⇒ If greater than
0.3 V
Repair the short to voltage on the
circuit. ⇓ If less
than 0.3 V
5. |
Test for infinite resistance
between the control circuit terminal 7 X2 at the K33 HVAC Control
Module harness connector and ground. |
⇒ If less than
infinite resistance
Repair the short to ground on the
circuit. ⇓ If
infinite resistance
6. |
Test for less than 5 Ω
between the K33 HVAC Control Module control circuit terminal 7 X2
and control circuit terminal 1 X1 at the E40 Electrical Auxiliary
Heater harness connector. |
⇒ If 5 Ω or
greater
Repair the open/high resistance in
the circuit. ⇓ If
less than 5 Ω
7. |
Replace the E40 Electrical
Auxiliary Heater and verify the DTC does not reset. |
⇒ If DTC
resets
Replace the K33 HVAC Control Module.
⇓ If DTC does not
reset
Electrical Auxiliary Heater Signal Circuit Malfunction
1. |
Ignition OFF, disconnect the
X2 harness connector at the K33 HVAC Control Module and the harness
connectors at the E40 Electrical Auxiliary Heater, ignition
ON. |
2. |
Verify that a test lamp
illuminates between the B+ circuit terminal 1 X2 at the E40
Electrical Auxiliary Heater harness connector and ground.
|
⇒ If the test lamp
does not illuminate and the circuit fuse is good
|
2.2 |
Test for less than 2 Ω
in the B+ circuit end to end. |
⇒ |
If 2 Ω or greater, repair the open/high resistance in the
circuit. |
⇒ |
If less than 2 Ω, verify the fuse is not open and there
is voltage at the fuse. |
⇒ If the test lamp
does not illuminate and the circuit fuse is open
|
2.2 |
Test for infinite resistance
between the B+ circuit and ground. |
⇒ |
If less than infinite resistance, repair the short to ground on
the circuit. |
⇒ |
If infinite resistance, replace the E40 Electrical Auxiliary
Heater. |
⇓ If the test lamp
illuminates
3. |
Verify that a test lamp
illuminates between the B+ circuit terminal 1 X2 and ground circuit
terminal 1 X3. |
⇒ If the test lamp
does not illuminate
Repair the open/high resistance in
the circuit. ⇓ If
the test lamp illuminates
4. |
Verify that a test lamp
illuminates between the ignition circuit terminal 2 X1 and ground
circuit terminal 1 X3. |
⇒ If the test lamp
does not illuminate and the circuit fuse is good
|
4.2 |
Test for less than 2 Ω
in the ignition circuit end to end. |
⇒ |
If 2 Ω or greater, repair the open/high resistance in the
circuit. |
⇒ |
If less than 2 Ω, verify the fuse is not open and there
is voltage at the fuse. |
⇒ If the test lamp
does not illuminate and the circuit fuse is open
|
4.2 |
Test for infinite resistance
between the ignition circuit and ground. |
⇒ |
If less than infinite resistance, repair the short to ground on
the circuit. |
⇒ |
If infinite resistance, replace the E40 Electrical Auxiliary
Heater. |
⇓ If the test lamp
illuminates
5. |
Test for less than 0.3 V
between the signal circuit terminal 5 X2 at the K33 HVAC Control
Module harness connector and ground. |
⇒ If greater than
0.3 V
Repair the short to voltage on the
circuit. ⇓ If less
than 0.3 V
7. |
Test for infinite resistance
between the signal circuit terminal 5 X2 at the K33 HVAC Control
Module harness connector and ground. |
⇒ If less than
infinite resistance
Repair the short to ground on the
circuit. ⇓ If
infinite resistance
8. |
Test for less than 5 Ω
between the K33 HVAC Control Module signal circuit terminal 5 X2
and signal circuit terminal 4 X1 at the E40 Electrical Auxiliary
Heater harness connector. |
⇒ If 5 Ω or
greater
Repair the open/high resistance in
the circuit. ⇓ If
less than 5 Ω
9. |
Replace the E40 Electrical
Auxiliary Heater and verify the DTC does not reset. |
⇒ If the DTC
resets
Replace the K33 HVAC Control Module.
⇓ If the DTC does
not reset
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|