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Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Suspension 🢒 Road Sensing Suspension (RSS) 🢒 DTC C1736 Compressor Relay Short to GND/Open CKT

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 low voltage condition at pin C15 during a compressor OFF-state.

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

Action Taken When the DTC Sets

The ELC 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 ELC compressor relay output is commanded to the OFF state, which occurs whenever compressor activity is not required. The control module expects to see a high voltage condition during the OFF-state.

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

    2.

  2. This step checks to see if ignition voltage is present.

    3.

  3. This step checks for an open circuit condition or short circuit to ground condition in CKT 321.

    4.

  4. This step checks for an internal open circuit condition in the relay coil.

    5.

  5. This step checks for an open circuit condition in CKT 147.

    6.

  6. This step checks for a short circuit to ground condition in CKT 147.

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. Check IGN-0 BODY fuse for a blown (open) condition. The IGN-0 BODY fuse is located in the rear compartment fuse block.

Is the fuse blown?

--

Go to Step 9

Go to Step 3

3

  1. Disconnect CVRSS control module connector C1.
  2. Turn the ignition ON with the engine off.
  3. Measure the voltage at pin C15 of CVRSS connector C1 (harness side).

Is the measurement greater than the specified value?

10 V

Go to Step 11

Go to Step 4

4

  1. Turn the ignition OFF.
  2. Check CKT 321 for a short circuit to ground condition or an open circuit condition.

Was a problem in CKT 321 found?

--

Go to Step 5

Go to Step 6

5

Repair the short or open circuit condition in CKT 321.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

6

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 7

Go to Step 13

7

Check for an open circuit condition in CKT 147.

Was an open circuit condition found?

--

Go to Step 8

Go to Step 11

8

Repair the open circuit condition in CKT 147.

Is the repair complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

9

Check for a short circuit to ground condition (continuity) between CKT 147 and ground.

Was a short to ground circuit condition found?

--

Go to Step 10

Go to Step 15

10

Repair the short circuit to ground condition between CKT 147 and ground.

Is the repair complete?

--

Go to Step 12

--

11
  1. Check all connections on CKTs 321 and 147 for debris, corrosion, and/or intermittent open circuit conditions.
  2. Check CKT 321 for an intermittent short circuit to ground condition. Refer to Intermittents and Poor Connections .
  3. Install all of the connectors and/or the components that were removed.
  4. Turn the ignition ON with the engine off.
  5. Clear the CVRSS DTCs. Refer to Clearing DTCs .
  6. Wait 60 seconds.
  7. Check the CVRSS DTCs. Refer to Displaying Diagnostic Trouble Codes (DTC) .

Is DTC C1736 set?

--

Go to Step 14

Go to Road Sensing Suspension Diagnostic System Check

12

Replace the IGN-0 BODY fuse.

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

13

Replace the ELC relay.

Is the replacement complete?

--

Go to Road Sensing Suspension Diagnostic System Check

--

14
  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

--

15

Replace the IGN-0 BODY fuse.

Is the replacement complete?

--

Go to Step 11

--