DTC 63

Fig. 151 Code 63: Valve Relay Fault (Part 1 Of 3).:

Fig. 151 Code 63: Valve Relay Fault (Part 2 Of 3).:

Fig. 151 Code 63: Vavle Relay Fault (Part 3 Of 3).:

DTC 63: Valve Relay Fault:

CIRCUIT DESCRIPTION
The valve relay provides power to the four ABS valve solenoids and two TCS Pilot Valves (if applicable) in the BPM valve. The valve relay is located on the BPM valve an may be replaced if it is found to be defective.

The valve relay is engaged during normal system operation. When the ignition is switched to RUN, the EBTCM/EBCM commands the valve relay ON by grounding the valve relay actuation line on CKT 856 (EBTCM/EBCM in "27"). When this ground is provided, the valve relay is energize from the voltage supply line on CKT 854 (EBTCM/EBCM pin 27). The valve reay switches and battery voltage is provided to the four valve solenoids, the pilot valves and the valve relay voltage sense line on CKT 886 (EBTCM/EBCM pin 23). The valve relay remains engaged until the ignition is turned OFF or a failure is detected.

The valve relay voltage feedback (EBTCM/EBCM pin 32) provides suppression of voltage spikes created during operation of both front ABS valve solenoids during antilock and traction control.

TEST CONDITION(S)
1. Tested continuously.

FAILURE CONDITION(S)
1. Less than 5 volts at EBTCM/EBCM pin 23, valve relay sense;
OR
2. Voltage at EBTCM/EBCM pin 23, valve relay sense remains high, although voltage at EBTCM/EBCM pin 27, valve relay control, is low (valve relay sticks).

ACTION TAKEN
1. Code set.
2. ABS/TCS switched OFF.
3. ANTILOCK indicator ON.
4. TRACTION DISABLED message displayed.

When the valve relay is engaged, the valve relay sense line should be at battery voltage. With the valve relay disengaged, the sense line should be at ground. If the commanded position of the valve relay and the position indicated by the sense line do not agree, Code 63 will set. Some conditions which will cause Code 63 to set are:
^ An open circuit on CKT 886 or 856.
^ A short to voltage on CKT 886 or 856.
^ A short to ground on CKT 886 or 856.
^ A defective solenoid valve relay.
^ Open circuit on CKT 854.
^ Loss of voltage to BPM valve terminals 6 and 12 during pump run.

TEST DESCRIPTION
Test numbers refer to circled numbers on the diagnostic chart.
1. Checks for availability of battery voltage to the Valve Relay through Maxi fuse 5 and CKT 1042.
2. Checks for possible loss of voltage current when system is under load. At Key-ON, system performs the power on Reset Test and cycles the valve relay, checking the current draw of valves.
3. Checks the Valve Relay coil for proper resistance.
4. Checks for the Valve Relay contacts being internally open when in the relay unenergized position.
5. Checks for the Valve Relay contacts being stuck open when in the relay-energized position.
5. Checks the integrity of the Valve Relay circuitry internal to the BPM valve.
6. Checks for an open in ground CKT 250.
7. Checks for an open in CKT 886.
8. Checks for an open between splice S140 and EBTCM/EBCM terminal "23".
9. Checks for a short to ground in CKT 886.
10. Checks for a short to system voltage in CKT 886.
11. Checks for an open in CKT 854.
12. Checks for a short to ground in CKT 854.
13. Checks for a short to system voltage in CKT 854. 14 Checks for an open in CKT 856.
15. Checks for a short to ground in CKT 856.
16. Checks for a short to system voltage in CKT 856.
17. Checks wiring and connectors for intermittents.
18. Determines whether the code was set due to an intermittent condition or an EBTCM/EBCM fault.
19. Checks if problem found in step 13 is due to a short to system voltage in CKT 874, 856, or 854.

DIAGNOSTIC AIDS
All tests using J 39700 Universal Breakout Box terminal 20 are using the terminal as ground. These tests, of course, assume that the ground CKT 1250 at terminal 20 is good.

It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the fault.