Temperature Gauge System

 CAUTION: Do not apply 12-volts or ground directly to the temperature sender terminal. This voltage will damage the sender.

1. Verify that the engine-to-body ground strap is secure. A poor ground can cause high temperature gauge indication.

2. Idle the engine, with all accessories off, until the thermostat opens and the engine coolant temperature stabilizes. The temperature gauge pointer should indicate in the lower half of the normal band. If the coolant temperature does not stabilize, check the cooling system for proper function.

3. Refer to diagnosis charts for diagnosis and testing of the magnetic temperature gauge system.

Coolant Warning

If the temperature indicating system is still not operating properly, check the engine coolant level to ensure that it is still at the full point. Also verify that thermostat is operating and that the automatic fan belt tensioner is within specification. Refer to Section 03-05.  

PINPOINT TEST B: TEMPERATURE GAUGE INOPERATIVE—POINTER DOES NOT MOVE

B1 VERIFY CONDITION

• Observe gauge performance.

• Does gauge pointer move?

GO to C1 for temperature gauge.

No
GO to B2.

 

B2 VERIFY CLUSTER PERFORMANCE

• With the ignition ON, observe the other gauges and warning indicators for proper operation.

• Do other gauges and warning indicators operate properly?

Yes
GO to D1.

No
GO to C1.

 

PINPOINT TEST C: TEMPERATURE GAUGE INACCURATE

 

C1 TEST SENDER CIRCUIT AT LOW  

• Insert Rotunda Instrument Gauge, System Tester 021-00055 or equivalent. Disconnect connector at sender and connect tester to cluster side of connector. Set to 74 ohms.

• Does gauge read 'C'?

Yes
GO to C2.

No
GO to C3.

 

C2 TEST SENDER CIRCUIT AT HIGH

• Set Gauge System Tester to 10 ohms.

• Does gauge read 'H'?

Yes
REPLACE sender.

No
GO to C3.

 

C3 CHECK SENDER CIRCUIT WIRING

• Check sender circuit wiring and cluster flex circuit for shorts or opens with Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent.

• Is wiring OK?

Yes
REPLACE gauge.

No
SERVICE wiring/flex circuit.

 

PINPOINT TEST D: TEMPERATURE GAUGE INOPERATIVE

 

D1 VERIFY POWER AT FUSE PANEL  

• Using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent verify system voltage at load side of warning indicator fuse.

• Is system voltage present at load side of fuse?

Yes
GO to E1.

No
GO to D2.

 

D2 VERIFY POWER AT FUSE PANEL

• Using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent verify system voltage at feed side of warning indicator fuse.

• Is system voltage present at feed side of fuse?

Yes
REPLACE fuse. GO to C1.

No
SERVICE wiring to fuse panel. GO to C1.

 

PINPOINT TEST E: OIL GAUGE INACCURATE

 

E1 TEST SENDER CIRCUIT AT LOW  

• Place ignition switch in the ON position with engine OFF. Observe gauge performance.

• Does gauge read 'L' or below?

Yes
GO to E2.

No
GO to E3.

 

E2 CHECK GAUGE RESPONSE

• Disconnect oil pressure switch and short the lead to engine ground.

• Does gauge indicate mid-scale or slightly above mid-scale?

Yes
REPLACE sender/switch.

No
GO to E3.

 

E3 CHECK SENDER/SWITCH WIRING

• Check sender/switch wiring and cluster flex circuit for shorts or opens using Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent.

• Is wiring/flex circuit OK?

Yes
REPLACE gauge. GO to A1.

No
SERVICE wiring/flex circuit. GO to A1.

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