Rear of Vehicle Low. Pontiac Bonneville 1998

GM Service Manual Online

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1998 🢒 Bonneville 🢒 Suspension 🢒 Automatic Level Control 🢒 Rear of Vehicle Low

Tools Required

J 22124-B Pressure Gage (0-300 psi)

Step

Action

Value(s)

Yes

DEFINITION: The rear of the vehicle will not raise, is always low, or leaks down when the vehicle is not used.

Is any aftermarket equipment installed on the vehicle that could affect the ALC system?

Go to Step 2

Go to Step 4

Check the aftermarket equipment to ensure that it is not affecting ALC performance.

Is the aftermarket equipment affecting the ALC performance?

Go to Step 3

Go to Step 4

Correct the condition.

Is the condition corrected?

Go to Automatic Level Control System Operation Check

Check the ELC fuse in the RH MaxiFuse® Block and the ABS/CCR fuse in the IP Fuse Block for an open (blown) condition.

Is the fuse open?

Go to Step 5

Go to Step 6

Replace the fuse. NOTE: If the fuse is open (blown) repeatedly, check CKT 641 (BRN) or CKT 1042 (RED) for a short circuit to ground condition.

Is the replacement complete?

Go to Automatic Level Control System Operation Check

Check the height sensor and link for proper connection and damage.

Are the height sensor and the link properly connected and in good condition?

Go to Step 8

Go to Step 7

Reconnect or replace the height sensor or the link. Refer to Automatic Level Control Sensor and Bracket Replacement .

Is the repair or replacement complete?

Go to Automatic Level Control System Operation Check

Does the vehicle leak down when the vehicle is not used for an extended period of time (overnight), but then come up to normal trim height with vehicle use?

Go to Step 28

Go to Step 9

Turn the ignition switch to the ON position.
Add approximately 300 lbs of weight to the rear of the vehicle.

Does the rear of the vehicle rise and not leak down? NOTE: Allow 27 seconds for the air compressor to start and then additional time for the struts to inflate.

Go to Step 10

Go to Step 12

Is the trim height at the rear underbody points correct? Refer to Trim Height in Suspension General Diagnosis.

Trim Height

Go to Automatic Level Control System Operation Check

Go to Step 11

Adjust the height sensor. Refer to Automatic Level Control Sensor Adjustment .

Is trim height at the rear underbody points correct? Refer to Trim Height in Suspension General Diagnosis.

Trim Height

Go to Automatic Level Control System Operation Check

Repeat this Step

Did the air compressor operate when weight was added?

Go to Step 28

Go to Step 13

Disconnect the height sensor electrical connector.
Turn the ignition switch to the ON position.
Connect a fused jumper from the height sensor connector (vehicle side) terminal B to ground.

Is the air compressor operating?

Go to Height Sensor Operational Check

Go to Step 14

Turn the ignition switch to the OFF position.
Connect the height sensor electrical connector.
Remove the ELC relay from the IP junction block.
Turn the ignition switch to the ON position.
Measure the voltage from the terminal where relay pin 85 was removed to ground.

Is battery voltage present?

Battery Voltage

Go to Step 16

Go to Step 15

Repair the open circuit condition in circuit 641 (BRN).

Is the replacement or repair complete?

Go to Automatic Level Control System Operation Check

Measure the voltage from the terminal where relay pin 30 was removed to ground (this terminal is hot at all times).

Is battery voltage present?

Battery Voltage

Go to Step 18

Go to Step 17

Repair the open circuit condition in circuit 1042 (RED) between the RH MaxiFuse® block and the IP junction block.

Is the repair complete?

Go to Automatic Level Control System Operation Check

Connect a voltmeter between the terminals where relay pins 85 and 86 were removed.
Turn the ignition switch to the ON position. NOTE: The ignition switch must be cycled if the ignition was left on from the previous step.

Is battery voltage present after 17 to 27 seconds (17 to 27 seconds is the height sensor delay period).

Battery Voltage

Go to Step 20

Go to Step 19

Check for a poor connection at the height sensor connector, terminal B, or an open-circuit condition in circuit 321.

Was a poor connection or open-circuit condition found and corrected?

Go to Automatic Level Control System Operation Check

Go to Height Sensor Operational Check

Connect a 30-amp fused jumper between the terminals where relay pins 30 and 87 were removed.

Is the air compressor operating?

Go to Step 21

Go to Step 22

Replace the ELC relay.

Is the replacement complete?

Go to Automatic Level Control System Operation Check

Leave the jumper from the previous step in place.
Disconnect the air compressor electrical connector.
Measure the voltage from the air compressor electrical connector (vehicle side), terminal C, to ground.

Is battery voltage present?

Battery Voltage

Go to Step 24

Go to Step 23

Repair the open-circuit condition in circuit 322 .

Is the repair complete?

Go to Automatic Level Control System Operation Check

Leave the jumper from the previous step in place.
Measure the voltage from the air compressor connector (vehicle side), terminal C, to the same connector, terminal A.

Is battery voltage present?

Battery Voltage

Go to Step 26

Go to Step 25

Repair the open-circuit condition in CKT 1250 (BLK).

Is the repair complete?

Go to Automatic Level Control System Operation Check

Disconnect the jumper and install the ALC relay.
Jumper the air compressor connector (compressor side), terminal A, to ground.
Jumper the air compressor connector (compressor side), terminal C to B+ using a 30-amp fused jumper wire.

Is the air compressor operating?

Go to Step 13

Go to Step 27

Replace the air compressor. Refer to Air Compressor Replacement .

Is the replacement complete?

Go to Automatic Level Control System Operation Check

Check the following:

•	Rear struts for a leaking air sleeve. NOTE: If the air sleeve is worn through, perform the Residual Air Pressure Check .

•	Air tube for kinks or pinched tubes.

•	Air tubes for a disconnected condition

•	All air tube connections using soap and water.

Was a leak or damage found and corrected?

Go to Automatic Level Control System Operation Check

Go to Step 29

Disconnect the air tube from the air dryer.
Connect the J 22124-B adapter tube to the air dryer.
Connect the J 22124-B gage to the J 22124-B adapter tube with the toggle valve on the opposite side (away from the air compressor) and closed.
Disconnect the air compressor electrical connector.
Jumper the air compressor electrical connector (compressor side), terminal A to ground.
Jumper the air compressor electrical connector (compressor side), terminal C, to B+ using a 30-amp fused jumper wire.
Allow the air compressor to operate until the pressure reaches 690 kPa (100 psi).
Disconnect the jumper from terminal A when 690 kPa (100 psi) is reached.

Is the air compressor able to reach it 690 kPa (100 psi)?

690 kPa (100 psi)

Go to Step 31

Go to Step 30

Replace the air compressor. Refer to Air Compressor Replacement .

Is the replacement complete?

Go to Automatic Level Control System Operation Check

Does the air pressure reading on the J 22124-B stay at 690 kPa (100 psi)?

690 kPa (100 psi)

Go to Step 32

Go to Air Compressor Leak Test

One of the following components is leaking:

•	Air Tube (air dryer to pressure limiter valve)

•	Pressure Limiter Valve

•	Air Tube (pressure limiter valve to crossover air tube or air inflator valve (vehicles equipped with optional inflator valve only)

•	Inflator Valve (vehicles equipped with optional inflator valve only)

•	Crossover Air Tube (routed between the struts)

Replace the component with the leak.

Is the replacement complete?

Go to Automatic Level Control System Operation Check