Ignition System Power Transistor
***UPDATED BY TSB #8903001, OCTOBER 5, 1989Intermediate Connector:
TEST AT INTERMEDIATE CONNECTOR
Power transistor testing may be done at intermediate connector H14, a 16 pin black connector located next to the battery. If testing at the intermediate connector fails, repeat testing at the transistor itself. If the transistor now tests good, check and correct faulty circuit between transistor and intermediate connector.
1. Disconnect high tension cable between ignition coil and distributor at distributor side.
2. Attach a spark plug test tool to the high tension cable from the coil. If a test tool is not available, hold the cable end 5-6mm (0.25in) from a metal surface with insulated pliers.
3. Turn ignition switch "ON."
4. Connect the positive end of a "D" size 1.5V battery to pin #4 (TF models) or pin #72 (KT models) of connector H14 on transistor side of the connector. Connect negative end of battery to ground.
5. As you connect and disconnect the battery from ground, a spark should jump across the plug tool gap or the air gap between high tension cable and ground. Repeat several times. If there is no spark, perform test at power transistor.
Power Transistor Test:
TEST AT POWER TRANSISTOR
1. Disconnect high tension cable between ignition coil and distributor at distributor side.
2. Attach a spark plug test tool to the high tension cable from the coil. If a test tool is not available, hold the cable end 5-6mm (0.25in) from a metal surface with insulated pliers.
3. With jack or hoist, raise the right front side of the vehicle and support with a jack stand. Remove the right front wheel.
4. Unsnap inner fender rubber cover.
5. Remove power transistor from bottom of intake manifold and separate the harness connector.
6. Connect a jumper lead from the harness side connector (terminal 71 on KT models; terminal 1 on TF models) to the power transistor connector (terminal 71 on KT models; terminal 1 on TF models).
7. Connect a second jumper lead from the power transistor connector (terminal 72 on KT models; terminal 2 on TF models) to the negative side of a 1.5V dry cell battery.
8. Connect a third jumper lead from the harness side connector (terminal 72 on KT models; terminal 2 on TF models) to the positive side of the dry cell battery.
9. Ground power transistor on vehicle frame.
10. Turn ignition switch "ON."
11. Disconnect and reconnect jumper lead at power transistor connector. A spark should occur across the tool gap or between the high tension cable and ground. Repeat several times. If there is no spark, replace the power transistor/bracket assembly.
If spark occurs during testing at the intermediate connector and at the power transistor (transistor tests okay), check wiring circuit as follows:
Connector Pin Numbers:
POWER TRANSISTOR CIRCUIT TEST
1. Check for voltage at the ignition coil:
a. If no voltage, check for voltage at fuse 14.
b. If there is voltage, check for power from ignition switch to fuse 14.
2. Check for voltage between power transistor and ignition coil.
3. With an ohmmeter, check circuit from power transistor to ECM N5 connector, pin #1. The meter should show continuity.
4. Measure same circuit to ground. There should be no continuity.
5. If a problem is detected, repair or replace the defective component.