DaimlerChrysler Jeep Grand Cherokee 2002 Service Manual page 232

DRIVEABILITY - DIESEL
*CHECKING THE GLOW PLUG OPERATION —
TEST
4 Turn the ignition off.
Disconnect the Glow Plug harness connectors of the affected cylinder(s).
Remove the Glow Plug Relay of the affected cylinder(s).
Turn the ignition on.
Measure the voltage on the Glow Plug Relay Output circuit of the affected cylinder(s).
Is the voltage above 1.0 volt?
Yes → Repair the Glow Plug Relay Output circuit for a short to voltage.
→ Go To 5
No
5 Turn the ignition off.
Disconnect the Glow Plug harness connectors of the affected cylinder(s).
Remove the Glow Plug Relay of the affected cylinder(s).
Measure the resistance between ground and the Glow Plug Relay Output circuit of
the affected cylinder(s).
Is the resistance above 100 kohms?
Yes → Go To 6
→ Repair the Glow Plug Relay Output circuit for a short to ground.
No
6 Turn the ignition off.
Disconnect the Glow Plug harness connectors of the affected cylinder(s).
Remove the Glow Plug Relay of the affected cylinder(s).
Connect a jumper wire across Glow Plug Relay connector cavities 30 and 87.
Using a 12-volt test light connected to ground, check the Glow Plug Relay Output
circuit at the Glow Plug harness connectors of the affected cylinder(s).
Is the test light on at each Glow Plug harness connector?
Yes → Go To 7
→ Repair the Glow Plug Relay Output circuit for an open.
No
7 If there are no possible causes remaining, view repair.
Repair
ACTION
Perform ROAD TEST VERIFICATION - VER-2.
Inspect the fuse or fuselink and replace as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
Perform ROAD TEST VERIFICATION - VER-2.
Replace the Glow Plug Relay of the affected cylinder(s).
Perform ROAD TEST VERIFICATION - VER-2.
Continued
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APPLICABILITY
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