Scan Tool Does Not Communicate with Theft Deterrent Module (Immobilizer)
WARNING: This page is about a different car, the 2000 Cadillac Catera. However, it is still accessible from the selected car via links, so may be relevant.
SCAN TOOL DOES NOT COMMUNICATE WITH THEFT DETERRENT MODULE (IMMOBILIZER)
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Was the Data Link Communications Diagnostic System Check performed? | -- | Go to Step 2 | Diagnostic System Check - Data Link Communications |
| 2 | Attempt to establish communication with the sun roof actuator. Does the scan tool communicate with the sun roof actuator? |
-- | Go to Step 3 | Go to Step 4 |
| 3 | 1. Disconnect the theft deterrent module (immobilizer) connector. 2. Measure the resistance between the connector terminal 8 and the data link connector (DLC) terminal 3. Does the resistance measure less than the specified value? |
.5 ohms | Go to Step 5 | Go to Step 6 |
| 4 | 1. Turn OFF the ignition. 2. Disconnect the scan tool from the DLC. 3. Inspect for poor connections/terminal tension at the DLC terminal 3. Refer to TESTING FOR INTERMITTENTS & POOR CONNECTIONS Did you find and correct a poor connection condition? |
-- | Go to Step 7 | Go to Step 8 |
| 5 | Inspect for poor connections at the immobilizer connector terminal 8. Refer to TESTING FOR INTERMITTENTS & POOR CONNECTIONS Did you find and correct a poor connection condition? |
-- | Go to Step 7 | Go to Step 9 |
| 6 | Locate and repair an open in the immobilizer serial data circuit. Is the repair complete? |
-- | Go to Step 7 | -- |
| 7 | Attempt to establish communications with the immobilizer. Does the scan tool communicate with the immobilizer? |
-- | System OK | -- |
| 8 | 1. Disconnect the sun roof actuator connector. 2. Attempt to communicate with the immobilizer. Does the scan tool communicate with the immobilizer? |
-- | Go to Step 10 | Go to Step 11 |
| 9 | 1. Inspect and test the immobilizer ignition feed circuit at terminal 5 for proper voltage (11-13 V). Turn ON the ignition, leaving the engine OFF, when testing for voltage. 2. Inspect and test the immobilizer battery feed circuit at terminal 9 for proper voltage (11-13 V). 3. Inspect and test the ground circuit at terminal 4. 4. Make necessary repairs. Did you find and correct any conditions? |
-- | Go to Step 7 | Go to Step 12 |
| 10 | Replace the sun roof actuator. Is the replacement complete? |
-- | Go to Step 7 | -- |
| 11 | 1. Disconnect each module on the serial data circuit (DLC terminal 3). 2. Test the serial data circuit, of the DLC, for a short to ground. 3. Test between terminal 3 and the following terminals at each module. * Immobilizer connector terminal 8 * Sun Roof Actuator terminal 4 Did you find a short to ground in the serial data circuit? |
-- | Go to Step 13 | Go to Step 14 |
| 12 | Replace the immobilizer. Is the replacement complete? |
-- | Go to Step 7 | -- |
| 13 | Locate and repair the short to ground in the serial data circuit. Is the repair complete? |
-- | Go to Step 7 | -- |
| 14 | Test the serial data circuit, of the DLC, for a short to voltage between terminal 3 and each module. (Turn ON the ignition, leaving the engine OFF, when testing for a short to voltage.) * Immobilizer connector terminal 8 * Sun Roof Actuator connector terminal 4 Did you find a short to voltage in the serial data circuit? |
-- | Go to Step 15 | Go to Step 16 |
| 15 | Locate and repair the short to voltage in the serial data circuit. Is the repair complete? |
-- | Go to Step 7 | Go to Step 8 |
| 16 | 1. Reconnect all disconnected modules. 2. Reconnect any other disconnected connectors. 3. Install the scan tool. 4. Turn ON the ignition, leaving the engine OFF. 5. Attempt to establish communications with the immobilizer. Does the scan tool communicate with the immobilizer? |
-- | Go to Step 17 | Go to Step 12 |
| 17 | It is apparent that the module communication condition is intermittent. Refer to the following: * TESTING FOR INTERMITTENTS & POOR CONNECTIONS Did you find and correct the condition? |
-- | Go to Step 7 | -- |