Rear of Vehicle Low. Cadillac Seville 2002

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2002 🢒 Seville 🢒 Suspension 🢒 Automatic Level Control 🢒 Rear of Vehicle Low

Rear of Vehicle Low w/o F45 or F55

Step	Action	Yes	No
Schematic Reference: Automatic Level Control Schematics
1	Did you review the Automatic Level Control System Description and Operation and perform the necessary inspections?	Go to Step 2	Go to Symptoms - Automatic Level Control
2	Turn ON the ignition, with the engine OFF. Add a load of 135 kg (300 lbs) to the rear of the vehicle. Does the automatic level control (ALC) compressor operate?	Go to Step 3	Go to Step 4
3	Does the rear of the vehicle rise and not leak down?	Go to Automatic Level Control Sensor Adjustment	Go to Automatic Level Control System Leak Test
4	Disconnect the automatic level control sensor connector. Connect a test lamp between the battery positive voltage circuit of the automatic level control (ALC) sensor and a good ground. Does the test lamp illuminate?	Go to Step 5	Go to Step 14
5	Connect a test lamp between the battery positive voltage circuit and the ground circuit of the ALC sensor. Does the test lamp illuminate?	Go to Step 6	Go to Step 15
6	Connect a test lamp between the automatic level control relay coil supply voltage circuit and a good ground. Does the test lamp illuminate?	Go to Step 7	Go to Step 11
7	Connect a 10 amp fused jumper wire between the automatic level control relay coil supply voltage circuit and a good ground. Does the ALC activate?	Go to Step 16	Go to Step 8
8	Leave the 10 amp fused jumper wire connected between the automatic level control relay coil supply voltage circuit and a good ground Disconnect the ALC compressor connector. Connect a test lamp between the automatic level control compressor motor control circuit and a good ground. Does the test lamp illuminate?	Go to Step 10	Go to Step 9
9	Test the automatic level control compressor motor control circuit for a short to ground or an open. Did you find and correct the condition?	Go to Step 19	Go to Step 13
10	Test the ALC compressor harness for a poor connection or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs or Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 18
11	Test the automatic level control relay coil supply voltage circuit for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 12
12	Test the ignition 3 voltage circuit to the ELC relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 17
13	Test the battery positive voltage circuit to the ELC relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 17
14	Repair the open in the battery positive voltage circuit to the ALC sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 19	--
15	Repair the open in the ALC sensor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 19	--
16	Replace the ALC sensor. Refer to Automatic Level Control Sensor and Bracket Replacement . Did you complete the replacement?	Go to Step 19	--
17	Replace the ELC relay. Did you complete the replacement?	Go to Step 19	--
18	Replace the ALC compressor. Refer to Air Compressor Replacement . Did you complete the replacement?	Go to Step 19	--
19	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3

Rear of Vehicle Low w F45 or F55

Step

Action

Yes

Schematic Reference: Automatic Level Control Schematics

Did you perform the Automatic Level Control (ALC) Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Automatic Level Control

Turn the ignition ON with the engine OFF.
Listen for the ALC air compressor to activate.

Does the air compressor come on within 30 seconds?

Go to Step 8

Go to Step 3

Turn the ignition OFF.
Disconnect the ALC connector from the ALC air compressor assembly.
Disconnect the Electronic Suspension Module connector.
Turn the ignition ON.
Connect a fused jumper between the ALC relay coil supply voltage circuit and ground.
Measure the voltage between the ALC compressor motor control circuit and ground.

Does the voltmeter display a voltage greater than 10 volts?

Go to Step 4

Go to Step 6

Remove the fused jumper wire.
Turn the ignition OFF.
Test the ground circuit of the ALC air compressor connector for a ground.

Did you find and correct the condition?

Go to Step 13

Go to Step 5

Replace the ALC air compressor assembly. Refer to Air Compressor Replacement .

Is the repair complete?

Go to Step 11

Remove the fused jumper wire.
Turn the ignition OFF.
Check for the following:

•	Open ELC fuse

•	Bad ELC relay

•	Open circuit in ALC air compressor motor control circuit

•	Open circuit in ALC relay coil supply voltage circuit

Was a problem found?

Go to Step 7

Important: A open fuse may indicate:

•	No head relief--check for ALC codes.

•	A faulty air compressor

•	A short to ground in the exhaust solenoid battery positive circuit

Repair the short to ground in the ALC compressor battery positive circuit or replace the fuse.

Is the repair complete?

Go to Step 13

Inspect the left and right rear position sensors for damage and disconnected links.

Are any damaged sensors or disconnected links present?

Go to Step 12

Go to Step 9

Perform the ALC System Leak Test.

Is a leak present?

Go to Step 10

Go to Step 11

Repair the leak in the ALC System.

Is the repair complete?

Go to Step 13

Turn the ignition OFF.
Connect the scan tool.
Turn the ignition ON with engine OFF.
Perform the CVRSS/ALC recalibration procedure.

Has the recalibration been completed?

Go to Step 13

Replace the damaged rear position sensor or reconnect the link.

Is the replacement complete?

Go to Step 13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1