Pinpoint Test A: Retrieving Diagnostic Trouble Codes (DTC) & VAPS Module Check

Module Check

Ensure ignition is off. Locate Data Link Connector (DLC) near brake booster. Connect voltmeter leads to circuit No. 606 (White/Light Blue wire) and ground. See Fig 1. Start engine. Observe voltage readings. If voltage is 11-14 volts, go to step 4). If voltage is not as specified, go to next step.

Fig 1: Identifying Diagnostic Connector Terminals

Module Check (Voltage Zero)

Repeat vehicle set-up as in step 1). Observe voltage readings. If zero volts is indicated, go to step 4). If voltage is indicated, go to next step.

Module Check (Greater Than 14 Volts)

Repeat vehicle set-up as step 1). Observe voltage readings. If more than 14 volts is indicated, correct overcharging condition. If 14 volts or less is indicated, go to next step.

Module Check (Effort Change 2 Sweeps)

Turn ignition off. Connect voltmeter as in step 1). Using jumper wire, ground circuit No. 200. Start engine. Rotate steering wheel in both directions for 90 seconds. Note changes in required turning effort. Effort should vary noticeably. After 90 seconds, if system is okay, voltmeter will indicate a sweep pattern between battery voltage and zero. Pattern will repeat 4 times. After a 5-second delay, pattern will repeat. If steering effort changes with 2 sweeps, VAPS module is good. Go to step 13). If steering effort does not change with 2 sweeps, go to next step.

Module Check (No Effort Change 2 Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is no effort change with 2 sweeps, go to PINPOINT TEST C , step 1). If there is effort change, go to next step.

Module Check (Effort Change 4 Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is effort change with 4 sweeps, go to PINPOINT TEST D , step 2). If there is no effort change, go to next step.

Module Check (No Effort Change 4 Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is no effort change with 4 sweeps, go to PINPOINT TEST D , step 2). If there is effort change, go to next step.

Module Check (Effort Change 6 Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is effort change with 6 sweeps, go to PINPOINT TEST D , step 8). If there is no effort change, go to next step.

Module Check (No Effort Change 6 Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is no effort change with 6 sweeps, go to PINPOINT TEST D , step 1). If there is effort change, go to next step.

Module Check (Effort Change No Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is effort change with no sweeps, go to PINPOINT TEST D , step 8). If there is no effort change, go to next step.

Module Check (No Effort Change No Sweeps)

Repeat vehicle set-up as in step 4). Rotate steering wheel and observe voltmeter sweep pattern. If there is no effort change with no sweeps, go to PINPOINT TEST D , step 1). If there is effort change, go to next step.

Fuse Check

Inspect fuse No. 5 (15-amp) in fuse panel to left of steering column, beneath instrument panel. If fuse is okay, go to PINPOINT TEST D , step 1). If fuse is faulty, replace fuse and go to PINPOINT TEST A , step 1).

Test Drive

Ensure VAPS system is connected. Drive vehicle at speeds up to 55 MPH. Set cruise control. Note steering effort changes. Note speedometer operation. If steering effort changes evenly, system is okay. Diagnosis is complete. If steering effort does not change, go to next step.

Test Drive (Left-To-Right Effort)

Set up vehicle as in step 13). If steering effort is unbalanced between right and left, replace steering gear and repeat step 13). If there is no change in steering effort, system is good. Test is complete.