Savana 3500 V8-4.8L (2009)
Circuit/System Testing
Single Rear Window Defog Grid Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate rear window defogger grid.
2. Test for less than 1 ohm between the ground circuit terminal listed below and ground.
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RPO A12 rear window defogger grid ground terminal A
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RPO A18 rear window defogger grid ground terminal B
‹› If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, connect a test light between the control circuit terminal A and ground.
4. Command the rear window defogger ON and OFF by pressing and depressing the rear window defog switch. The test lamp should turn ON and
OFF when changing between the command states.
‹› If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace
the rear window defogger grid.
Rear Window Defogger Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the HVAC control assembly.
2. Test for less than 1 ohm between the ground circuit terminal C and ground
‹› If greater than the specified range, test the ground circuit for an open/high resistance
3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground.
‹› If the test lamp does not illuminate, test the B+ circuit for an open/high resistance
4. Ignition OFF, connect the harness connector at the HVAC control assembly and disconnect the REAR DEFOG relay.
5. Test for less than 1 ohm between the ground circuit terminal 85 and ground.
‹› If greater than the specified range, test the ground circuit for an open/high resistance.
6. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
‹› If the test lamp illuminates, test the control circuit for a short to voltage.
7. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
‹› If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
8. Ignition ON, connect a 30A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the rear window
defogger grids are activated.
‹› If the rear window defogger grids do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests
normal, test or replace the REAR DEFOG relay.
9. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
10. Command the rear window defogger grid ON and OFF by pressing and depressing the rear defogger switch. The test lamp should turn ON and
OFF when changing between the commanded states.
‹› If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the HVAC control assembly.
‹› If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the
HVAC control assembly.
11. If all circuits test normal, test or replace the REAR DEFOG relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the REAR DEFOG relay.
2. Test for 60-180 ohms between terminals 85 and 86.
‹› If not within the specified range, replace the relay.