AHE test of electrical system auxiliary heater control module undervoltage

AD83.70-W-6000-52A

AHE test of electrical system auxiliary heater control module undervoltage





Scope of test

Measuring instrument/

Test connection

Operation/Requirement

Specified value

 Possible cause/Remedy

1.0



Control unit (Z14)

Undervoltage



Ignition: ON

Erase fault code.

Check HHT actual value 03 

AD83.70-W-3006A

22.529.5 V

Value < 19 V:

 1.1

Value in order:

 Erase fault code (starter possibly actuated with heater unit switched on).

 If fault code  re-appears, replace control unit (Z14) on trial.

1.1

Control unit (Z14)

Undervoltage





Test module

Terminal 30

Ignition: ON

Open electrical compartment and install test module.

Carry out measurement at test module.

 Check voltage on battery poles if necessary.

22.529.5 V

Value < 19 V:

 Charge vehicle batteries, replace if necessary.

Value in order:

 Check voltage supply (B3, B8) and ground connection (B4) on control unit (Z14).

 Inspect plug connections on unit mount (behind timer), on control unit, on timer, in blower box, under electrical compartment and on heater unit (above right front fender) (possible contact resistance due to corrosion).