Coolant Shutoff Valve - Open Circuit/Short Circuit to Ground, Short Circuit to B+

P1656

Coolant shutoff valve - open circuit/short circuit to ground, short circuit to B+

Function
The ATF is cooled via an ATF-water heat exchanger fastened on the transmission.
The Tiptronic control module controls the coolant shutoff valve depending on the temperature of the ATF and the coolant temperature. This coolant shutoff valve connects vacuum to the flat-seat valve and opens or closes the transmission coolant circuit.
The coolant shutoff valve is activated at an ATF temperature [>] 85 °C or a coolant temperature [>] 90 °C and deactivated at an ATF temperature [<] 75 °C and a coolant temperature [<] 80 °C.

Fault effect:
In the case of open circuit/short circuit to ground = activation of the fault lamp (4th gear and selector lever position flash).

In the case of short circuit to B+ = Fault is only entered in the fault memory.

Diagnosis conditions
- Starting process (in the case of short circuit to B+)
- Driving operation, ATF temperature [>] 85 °C or coolant temperature [>] 90 °C (in the event of open circuit/short circuit to ground)

P1656:

Wiring diagram







Diagnosis procedure

NOTE: The function of the coolant shutoff valve can be tested with the Porsche System Tester 2 (Drive links/Coolant shutoff valve). The triggering pulse of the valve can be heard as a clicking sound.







1 Check coolant shutoff valve.

1. Pull off connector on coolant shutoff valve
2. Connect ohmmeter to coolant shutoff valve pins 1 and 2.

Display: 25... 35 Ohms

2 Check wiring from Tiptronic control module to coolant shutoff valve for continuity.

1. Pull off Tiptronic control module connector.
2. Connect ohmmeter to Tiptronic control module connector pin 51 and coolant shutoff valve connector pin 1.

Display: 0... 5 Ohms

If Infinity Ohm is displayed, check wiring harness for chafing and pinching damage.

2 Check wiring from Tiptronic control module to coolant shutoff valve for short circuit to ground.

1. Connect ohmmeter to Tiptronic control module connector pin 51 and ground.

Display: Infinity Ohm

If 0... 5 Ohms is displayed, check wiring harness for chafing and pinching damage.

2 Check wiring from Tiptronic control module to coolant shutoff valve for short circuit to B+.

1. Switch on ignition.
2. Connect voltmeter to Tiptronic control module connector pin 51 and ground.

Display: 0 Volt

If battery positive voltage is displayed, check wiring harness for chafing and pinching damage.