Test 04 - Dynamic Voltages

ABS Test Equipment:

TEST SEQUENCE
1. Connections needed:
- T-plug (4a) with adapter (A) at Antilock Brake System (ABS) wire harness (1)
- T-plug (4b) at ABS control unit (2)
- Connecting lead at adapter (A) to cigarette lighter - red telltale lamp comes "On"
- Switch position at adapter (A) on '3' model and test step 04 (left)
2. Switch "On" ignition - ABS telltale lamp in combined instrument and lamp D+ at adapter (A) must light up.
3. When brake pedal is depressed, the second (green) lamp at adapter (right) must light up.





Nominal Values

4. Compare the displayed actual values obtained from the test equipment with the nominal values provided above. If nominal values are not obtained, proceed with the troubleshooting procedures below as needed.

TROUBLESHOOTING

CAUTION: Turn "Off" ignition before pulling off a connector to measuring resistance.

Voltage Between Wires 1 And 10
- Ignition turned "On".
- Engine running.
- Battery charged (check).
- Voltage drop checked at: battery Connection (+ and -) term. 15 and from ignition lock to control unit wire 1.

Stab, Voltage Between Wires 12 And 10
- Check function of Overvoltage relay.
- Replace control unit.
- Also refer to test step 05 test line 2.

Valve Relay Home Contact Voltage Drop
1. Replace valve relay.
2. Ground Connection has excessive resistance or break.
3. Check flow in following wires: wire 8 from ground to hydraulic unit plug. From hydraulic unit wire 8 to wire 87a, flow from wire 4 to valve relay terminal 30, from wire 4 to multiple pin plug (control unit) wire 32.

Valve Relay Opening Contact Voltage Drop
1. Replace valve relay.
2. Check flow in following wires: wire 6 from term. B + to hydraulic unit plug, from wire 6 to valve relay wire 87, from wire 2 to multiple pin plug (control unit) wire 27, from hydraulic unit wire 2 to valve relay wire 85, from wire 86 (valve relay) to wire 86 (motor relay) and wire 10, from hydraulic unit wire 10 to overvoltage relay terminals 30a or 30.

Motor Relay Operating Contact Voltage Drop
1. Replace motor relay.
2. Check ground terminals of pump motor for tight fit and transmission resistance.
3. Check flow in following wires: from term. B + to plug hydraulic unit wire 12, from multiple pin plug (control unit) wire 14 to hydraulic unit plug, from wire 9 in hydraulic unit to motor relay term. 30 and positive terminal on pump motor.
4. Pump motor defective:

Replace hydraulic unit.

Safety Circuit Lamp, Diode
- Check wire 29 from multiple pin plug (control unit) to hydraulic unit plug for break and voltage drop. Check plug connection on indicator lamp. Valve relay plugged in? Pull off hydraulic unit plug. Diode test between wires 7 and 4 (M 09)

Replace hydraulic unit.

- Excessive voltage drop or break in wires:

Replace wire harness.