ABS Works But ABS Warning Light Comes On While Driving

Causes: Generator not charging properly. Charging signal at D+ from generator absent, i.e. short-circuit to 0 volts or open-circuit in lead. Short-circuit in control lead to ABS warning light (dashboard terminal B:4).

CHECKING GENERATOR VOLTAGE (D+)
1. Ignition off.
2. Connect test box between control module and ABS system connector.
3. Connect a voltmeter between # 20 (0 volts) and # 15 on test box.
4. Ignition on. Voltmeter should read approx. 2 volts.
5. Start engine. Voltmeter should read approximately 14.5 volts.

NOTE: If voltmeter reading is correct in both cases: Check lead between connector C2 and dashboard, pin C16, for open-circuit.

NOTE: If voltmeter reads approx. 10 volts in both cases: Open-circuit in lead from generator (D+) to control module pin 15. See appropriate circuit diagram at back of manual. Treat open-circuit. Than go below to Checking lead between generator (D+) and control module (open-circuit).

NOTE: If voltmeter reading is approx. 0 volts in both cases: Short-circuit to 0 volts in lead from generator (D+) to control module pin 15. See below.

CHECKING FOR SHORT-CIRCUIT TO O VOLTS IN LEAD BETWEEN GENERATOR (D+) AND CONTROL MODULE
1. Ignition off.
2. Disconnect control module from adapter.
3. Connect an ohmmeter between # 20 (0 volts) and # 15 on test box.
4. Meter reading should be at infinity. Go below to Checking lead between generator (D+) and control module (open-circuit).

NOTE: If reading is incorrect: Meter reading is O ohms. Short-circuit in lead.

Note: If there is a short-circuit, the charging indicator light will be on. Check leads for short-circuit to ground (O volts).

CHECKING LEAD BETWEEN GENERATOR (D+) AND CONTROL MODULE (OPEN-CIRCUIT)
1. Ignition off.
2. Connect test box to ABS system connector.
3. Connect an ohmmeter between pin C16 on dashboard and # 15 on test box. Meter reading should be approx. O ohms. Go below to Checking short-circuit to O volts in ABS warning light control circuit.

NOTE: If reading is incorrect: If the ohmmeter reads infinite resistance, this means there is an open-circuit in the lead. - Deal with open-circuit.

CHECKING SHORT-CIRCUIT TO O VOLTS IN ABS WARNING LIGHT CONTROL CIRCUIT
1. Ignition off.
2. Connect test box to ABS system connector.
3. Connect an ohmmeter across # 20 (0 volts) and # 29 on test box. Meter reading should be infinite.

NOTE: If reading is incorrect: If the ohmmeter reading is O ohms, there is a short-circuit in the lead. Check leads from short-circuit to ground (approx. O volts). (Alternatively, there may be a short-circuit in the diode in the valve relay. Try another relay.)