A/C - Erratic/Inoperative Auxiliary Heater Operation

Cayenne

2/03 8220

Binder - 8, Air Conditioning

Date: 12-18-03

Diagnosis And Repair Of The Auxiliary Heater

Vehicle Type:
Cayenne S/Cayenne Turbo

Model Year:
As of '03 (3)

Concerns:
Diagnosis and repair of the auxiliary water heater (auxiliary heater) (I No. 7VE, 7VL).





Information:
Below are instructions for troubleshooting complaints in relation to the auxiliary water heater system. Software version 16.0 or higher is required for the work with the Porsche System Tester 2 (PST2).

Note:
Low voltage cutoff (--> step 2, remedy for cause 1) can be changed in the auxiliary water heater control unit using the PST2 only with software version 17.0 or higher.

Work Procedure:

1. No reaction to the "Timer" button.

Cause 1: Software error in air conditioning control module.

Cause 2: Air-conditioning control module faulty.

Remedy: Replace air conditioning control module.

2. The auxiliary water heater cannot be started.

Cause 1: The auxiliary water heater does not start because the battery positive voltage is 12.2 V
or lower (--> Undervoltage cutoff of the auxiliary water heater). Fault memory entry
"1444 - Undervoltage cutoff" in the auxiliary water heater control unit.

Remedy: Charge the battery or replace it if faulty. Change the undervoltage cutoff from "External"
to "Internal" in the auxiliary water heater control unit using the PST2 (--> PST2 software
version 17.0 or higher required).

Cause 2: The auxiliary water heater was disabled or switched off by a protective function. This protective function is stored as an entry in the auxiliary water heater control unit (e.g. "1406 - No firing" or "2251 - Control unit disabled").

Remedy: Read out the fault memory with the PST2. Remedy the fault or faults as described in the Cayenne Technical Manual, Group 8, Repairs, Chapter 82-12 - Fault overview - auxiliary heater. The auxiliary water heater must then be re-enabled using the PST2; clear fault entries from the fault memory.

Cause 3: An auxiliary water heater control unit with software version "0119" or lower is installed.

Remedy: Read out the software version of the auxiliary water heater control unit using the PST2. If the software version is "0119" or lower, the auxiliary water heater must be replaced.

3. No reaction to signals from the remote control.

Cause 1: The batteries for the remote control are dead or faulty.

Remedy: Replace both batteries in the remote control.

Cause 2: The remote control is not programmed.

Remedy: Program the remote control with the PST2.

4. No reaction to the remote control at greater distances.

Cause 1: The batteries for the remote control are nearly dead or faulty.

Remedy: Replace both batteries in the remote control.

Cause 2: The antenna of the radio receiver for the auxiliary water heater is not connected.

Remedy: Connect the antenna of the radio receiver and check the wiring.





Parts Information:

Literature:
Cayenne Technical Manual, Group 8:
> Repairs: 82-12 - Fault overview - auxiliary heater

Technical Information Bulletin - Group 8. # 4/03 - Auxiliary Heater Cannot Be Programmed





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