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Home >> Cadillac >> 2006 >> XLR Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 4.6L (LH2) - DTC P0651 To P2122 >> DTC P0686 >> Test Description

Test Description

  1. 3:  The engine will crank and run, with a short to ground on the ignition 1 relay coil control circuit. This condition could result in a discharged battery.
  2. 5:  The engine will crank but will not run, with a high resistance or an open on the ignition 1 relay coil control circuit.
DTC P0686

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Engine Control Module Connector End Views and Engine Controls Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.
Did the DTC fail this ignition?		 - Go to Step 3  Go to Intermittent Conditions
3  Attempt to start the engine.
Does the engine start and run?		 - Go to Step 6  Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Remove the ignition 1 relay from the underhood fuse block with the J 43244  Relay Puller Pliers. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) .
    3. NOTE: Refer to Test Probe Notice .
  3. Probe the battery positive voltage terminal for the ignition 1 relay coil at the underhood fuse block with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp .
Does the test lamp illuminate?		 - Go to Step 5  Go to Step 10 
5 
  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 relay coil control circuit terminal at the underhood fuse block with a test lamp that is connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 9  Go to Step 17 
6
  1. Turn OFF the ignition.
  2. Remove the ignition 1 relay from the underhood fuse block with the J 43244  . Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) .
    3. NOTE: Refer to Test Probe Notice .
  3. Probe the ignition 1 relay coil control circuit terminal at the underhood fuse block with a test lamp that is connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 7  Go to Step 11 
7
  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM) electrical connector that contains the ignition 1 relay coil control circuit. Refer to Engine Control Module Replacement .
    3. NOTE: Refer to Test Probe Notice .
  3. Probe the ignition 1 relay coil control circuit terminal at the underhood fuse block with a test lamp that is connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 8  Go to Step 13 
8
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection .
  3. Disconnect the underhood fuse block electrical connector that contains the ignition 1 relay coil control circuit. Refer to Underhood Electrical Center or Junction Block Replacement .
  4. Connect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection .
  5. Probe the ignition 1 relay coil control circuit terminal at the underhood fuse block electrical connector with a test lamp that is connected to battery positive voltage.
Does the test lamp illuminate?		 - Go to Step 14  Go to Step 19 
9
  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection .
  3. Disconnect the underhood fuse block electrical connector that contains the ignition 1 relay coil control circuit. Refer to Underhood Electrical Center or Junction Block Replacement .
  4. Disconnect the ECM electrical connector that contains the ignition 1 relay coil control circuit. Refer to Engine Control Module Replacement .
  5. Measure the resistance of the ignition 1 relay coil control circuit from the underhood fuse block electrical connector to the ECM electrical connector with a DMM. Refer to Troubleshooting with a Digital Multimeter .
Does the resistance measure greater than the specified value?		 5 Ω Go to Step 17  Go to Step 11 
10 Probe the mounting stud for the battery positive cable at the underhood fuse block with a test lamp that is connected to a good ground.
Does the test lamp illuminate?		 - Go to Step 19  Go to Step 15 
11 Measure the resistance from terminal #85 of the ignition 1 relay to terminal #86 with a DMM. Refer to Troubleshooting with a Digital Multimeter .
Does the resistance measure within the specified range?		 70-110 Ω Go to Step 12  Go to Step 18 
12 Test for an intermittent and for a poor connection at the ignition 1 relay location of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections .
Did you find a condition?		 - Go to Step 19  Go to Step 13 
13 Test for shorted terminals and poor connections at the ECM electrical connectors. Refer to Testing for Intermittent Conditions and Poor Connections .
Did you find and correct the condition?		 - Go to Step 21  Go to Step 20 
14 Repair the short to ground in the ignition 1 relay coil control circuit between the underhood fuse block electrical connector and the ECM electrical connector. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 21  -
15 Test for an intermittent and for a poor connection in the battery positive cable between the underhood fuse block and the battery.
Did you find and correct the condition?		 - Go to Step 21  Go to Step 16 
16 Replace the battery positive cable to the underhood fuse block. Refer to Battery Positive and Negative Cable Replacement (LH2) or Battery Positive and Negative Cable Replacement (LC3) .
Did you complete the replacement?		 - Go to Step 21  -
17 Repair the high resistance or an open in the ignition 1 relay coil control circuit between the underhood fuse block electrical connector and the ECM electrical connector. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 21  -
18 Replace the ignition 1 relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) .
Did you complete the replacement?		 - Go to Step 20  -
19 Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement .
Did you complete the replacement?		 - Go to Step 21  -
20 Replace the ECM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?		 - Go to Step 21  -
21
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze/Frame Failure Records.
Did the DTC fail this ignition?		 - Go to Step 3  Go to Step 22 
22 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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