Ignition oil -  testing, removal and refitting

Ignition systems / Ignition oil -  testing, removal and refitting

Testing
1 The resistance of the coil windings may be tested without removing the unit from the engine bay. Note that the measurements taken will be affected by ambient temperature, so it is good idea to conduct this test after the engine has been running for a while, as the coil will then be at its normal operating temperature.

2 Disconnect the battery negative cable and position it away from the terminal.

3 Connect the probes of a multimeter set to the resistance measurement function across the primary winding terminals (1 and 15) (see illustration). Record the resistance indicated. Note: On G40 mode/s with a cylindrical ignition coil, the primary resistance is measured between the ‘+’ and ´-’ terminals.

3.3 Ignition coil primary and secondary winding terminals

A Primary winding terminals B Secondary winding terminals

4 Repeat the measurement at the secondary winding terminals (4 and 15) (refer to illustration 3.3). Note: On G40 models with a cylindrical ignition coil, the secondary resistance is measured between the HT lead terminal and ‘-’ terminal.

5 Compare the measurements with the Specifications and renew the coil if necessary.

Note: This test pinpoints short or open circuits within the ignition coil, but does not a/low diagnosis of failures that occur whilst the coil is under load. Under these circumstances, the coil should be tested by an automotive electrical specialist.

Removal
6 On all models, the ignition coil is mounted at the front left hand corner of the engine bay.

7 Disconnect the battery negative cable and position it away from the terminal.

8 Unplug the HT lead from the ignition coil at the connector (see illustration).

3.8 Ignition coil connectors

A HT cable connector B LT cable multiway connector

9 Disconnect the LT cable from the ignition coil at the multiway connector (refer to illustration 3.8).

10 Slacken and withdraw the mounting screws, remove the brackets and detach the earthing strap (where applicable). Remove the ignition coil from the engine bay.

Refitting
11 Refitting is a reversal of removal.