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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Suspension 🢒 Road Sensing Suspension (RSS) 🢒 DTC C1735 Compressor Relay Short to Battery

Object Number: 258336 Size: MF

Circuit Description

The compressor is switched ON and OFF via an ELC compressor relay which is controlled by the CVRSS control module. The control module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit is also continually monitored to determine if the voltage level agrees with the commanded state.

Conditions for Setting the DTC

The DTC is set when the CVRSS control module sees a high voltage condition at pin C15 during a compressor ON-state.

The DTC will turn HISTORY when the CVRSS control module no longer senses a high voltage condition at pin C15 while the ELC compressor relay output drive is in an ON-state.

Action Taken When the DTC Sets

The compressor relay output drive is disabled for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
    • Use the scan tool.
    • Refer to the CLEAR RSS CODES feature.

Diagnostic Aids

This fault condition is detectable only when the compressor relay output is commanded to the ON-state, which occurs during the Air Replenishment Cycle (ARC) and whenever an upward correction is necessary. The control module expects to see a low voltage condition during the ON-state.

Only electrical problems with the compressor relay coil circuit are flagged. The compressor motor problems and pneumatic leakage problems do not set a DTC, but the CVRSS control module shuts the compressor relay off if there is no progress, or if excessive run times occur. Recovery is not attempted until the ignition is cycled OFF, then ON.

Test Description

Important: 

   • Do not backprobe the sensors, actuators, or any sealed connectors.
   • When all the diagnostics and repairs are complete, clear the DTCs and verify the operation.

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks for an internal open circuit condition in the ELC relay.

    2.

  2. This step checks for a short to voltage condition in CKT 321.

Step

Action

Value(s)

Yes

No

1

Was the CVRSS System Check performed?

--

Go to Step 2

Go to Road Sensing Suspension Diagnostic System Check

2

  1. Turn the ignition OFF.

    2. Remove the ELC Relay.

  2. Measure the resistance between pin A3 and pin B1 of the ELC relay (device side).

Is the measurement within the specified values?

45-49 ohms

Go to Step 3

Go to Step 8

3

  1. Turn the ignition ON with the engine off.
  2. Measure the voltage at pin B1 of the ELC relay socket (harness side).

Is the measurement greater than the specified value?

10 V

Go to Step 5

Go to Step 4

4
  1. Check CVRSS control module connector C1 and the ELC relay and socket for debris and corrosion.
  2. Install the ELC relay and all of the connectors.
  3. Clear the DTCs. Refer to Clearing DTCs .
  4. Wait 60 seconds.
  5. Check the RSS DTCs. Refer to Displaying Diagnostic Trouble Codes (DTC) .

Is DTC C1735 CURRENT?

--

Go to Step 9

Go to Step 6

5

Repair the short to voltage condition in CKT 321.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

6

Check for an intermittent short to voltage condition in CKT 321.

Is an intermittent short to voltage condition present?

--

Go to Step 7

Go to Road Sensing Suspension Diagnostic System Check

7

Repair the intermittent short to voltage condition in CKT 321.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

8

Replace the ELC relay.

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

9
  1. Turn the ignition OFF.
  2. Replace the CVRSS control module. Refer to Electronic Suspension Control Module Replacement .
  3. Install all of the connectors and components that were removed.
  4. Install the scan tool.
  5. Turn the ignition ON with the engine off.

    6. Important: The controller must be calibrated.

  6. Calibrate the CVRSS service controller using the scan tool. Refer to Electronic Suspension Control Module Calibration .

Is the CVRSS control module calibrated?

--

Go to Road Sensing Suspension Diagnostic System Check

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