Wiring and Components, Checking with Test Box VAG 1598/31

Wiring and Components, Checking with Test Box VAG 1598/31


If it is not specifically mentioned in a particular component check whether the test box should be connected to the Engine Control Module (ECM) 1 wiring harness or Engine Control Module (ECM) 2 wiring harness, refer to the wiring diagram.

For example, if checking wiring from Knock Sensor (KS) 1 (-G61-) "to engine control module" (this example does not specify if wires to engine control module 1 or 2 should be checked), then refer to electrical wiring diagram to see that Knock Sensor (KS) 1 (-G61-) is connected to ECM 1.

Logically, this indicates that the test box should be connected to the engine harness that leads to ECM 1.

• The test box (V.A.G 1598/31) is designed so that it can be connected simultaneously to the engine control module harness and the engine control module itself.





• This makes it possible for the electronic engine control to remain fully functional with the test box attached (e.g. measurement of signals with engine running).

• The procedures will indicate whether the engine control module is to remain connected to the test box or not.

• For testing, use multimeter (V.A.G 1526) or multimeter (V.A.G 1715) or an equivalent as well as the diode test lamp (V.A.G 1527B).

• To connect testing devices to the test box (V.A.G 1598/31), always use adapters from connector test set (V.A.G 1594).

CAUTION!
To avoid damaging electronic components, switch to the corresponding measuring range and observe all test conditions before connecting the test leads.

Test box (V.A.G 1598/31), connecting

- Remove right cover from plenum chamber.

Removing Engine Control Module (ECM)

• The two engine control modules look identical. If both engine control modules are removed, they must be marked before removal to prevent them from being interchanged when re-installing.

• Master ECM 1: e.g. with a "M"

• Slave ECM 2: e.g. with a "S"

Position 1 shows the Master ECM (J623).

Position 2 shows the Slave ECM 2 (J624).





The removal procedure is the same for both engine control modules.

To increase the difficulty with which the ECM connectors can be accessed, the ECM - 1 - is secured in a metal housing - 5 - with retaining tabs - 2 - and shear bolts - 3 - and - 4 -.





Tools required

• Heat gun - 1 - (from wiring harness repair kit (VAS 1978))

• Nozzle attachment - 2 - (also from wiring harness repair kit (VAS 1978))

• small, commercially available locking pliers (vise grips)- 3 -





CAUTION!
By heating the threads, the retaining tabs, shear bolts and parts of the metal housing become very hot. Do not burn yourself on these parts! Make sure that only the threads are heated as much as possible, and not any of the surrounding parts. If necessary, cover these parts.

The threads of the shear bolts - 4 - (not screwed into the ECM) are coated with a locking compound. For this reason, the threads must be heated with the heat gun to remove both bolts.

The threads of both shear bolts - 3 -, that are screwed into the ECM, are not coated with a locking compound. The threads in the ECM housing must not be heated (unintentional heating of the ECM).





- Set adjustment on heat gun as shown in illustration, with temperature potentiometer - 2 - set to maximum heat and two-stage air flow switch - 3 - set to level 3.





- Heat threads of connector-side shear bolts as shown in illustration for approx. 25 to 30 seconds.





CAUTION!
By heating the threads, the retaining tabs, shear bolts and parts of the metal housing become very hot. Do not burn yourself on these parts! Make sure that only the threads are heated as much as possible, and not any of the surrounding parts. If necessary, cover these parts.

- Remove shear bolts with locking pliers (see direction of arrow).





• Both shear bolts that are screwed into the ECM do not require heating to be removed. They can be removed without heat.

- Disconnect metal retainers from ECM connectors.

- Release and disconnect connector from Engine Control Module (ECM).

- Connect test box (V.A.G 1598/42) to wiring harness connector. Ground (GND) clip at test box must be clipped to battery Ground (-). Procedures will indicate whether ECM is to be connected to test box.

- Perform test as described in relevant repair sequences.

Installing Engine Control Module (ECM)

Perform installation in reverse order of removal. Thereafter, the ECM must be equipped with the protective housing. Always use new shear bolts.

• When ending Guided Fault-finding, the tester attempts to erase the Diagnostic Trouble Code (DTC) memory of all control modules. If this is not successful, the remaining DTCs stored in memory must be corrected until all DTCs can be erased.

Steps to perform after installing Engine Control Module (ECM)

The procedures to follow after connecting the new ECM are described in Guided Fault-finding.

- Follow instructions in Guided Fault-finding.

- Enter correct vehicle into Guided Fault-finding

- Press "Go to" button

- Select "Function/component selection"

- Select "powertrain"

- Select "engine code"

- "01 - On Board Diagnostic (OBD) capable systems

- "Motronic fuel injection and ignition system"

- Select "Functions"

- Select "Engine Control Module (ECM)"