Description

Transfer Box Interface Description

1. Fault Codes:
Transfer Box Fault P1701
Transfer Box Link Electrical Fault P1703
Transfer Box Link Short Circuit P1708

2. Monitoring Procedure

Electrical Checks
At pre-determined times following ignition key 'ON', the transfer box controller will drive the link to the ECM low and then high again in order to check for line integrity. Depending on the outcome of this test, electrical faults with the link can be determined.






The timing diagram image shows the requirements.

Transfer Box Fault
If the transfer box controller decides that it has a fault, then it will drive the link to the ECM low. The ECM will then turn the MIL on and store the appropriate fault codes.

3. Primary Detection Parameter
Digital (high/low) input from the Transfer Box Controller.

4. Fault Criteria Limits
Electrical Checks
The link must be driven low within 1.0s of ignition key 'ON' and then high again within a further 2.5s. The link must stay high for at least 2.0s. (See the timing diagram above.)
Transfer Box Fault
The transfer box controller must drive the link low for at least 2 secs before fault is stored.

5. Monitoring Conditions
The electrical checks are done after every ignition key 'ON'.
The electrical checks will be aborted if the battery voltage drops below 8V.
The system monitors for a Transfer Box fault all the time, provided there are no electrical faults.

6. Monitoring Time Length / Frequency of Checks
The electrical check takes 5.5secs and is done once after ignition key 'ON'
While looking for a Transfer Box Fault, the link is monitored at a 10Hz sampling rate for the rest of the ignition 'ON' cycle.

7. Criteria for Storing Fault Code
A fault code will be stored immediately after detecting a fault.

8. Criteria for Illuminating MIL
The MIL will be illuminated immediately after detecting a fault.

9. Criteria for Determining Out of Range Input Signals
Electrical checks are performed as described above.