5.3.2.2 Temperature Gauges
Symptom - Gauge passes initialization but is inaccurate in actual use; pointer stays at
7:00 position with flashing LED; false warning message or alarm.
Probable Cause - Defective sensor or sensor wiring; defective Interface Module.
Gauge Types - Forward Axle, Rear Axle, Center Axle, 6X6 Front Axle, Main Trans-
mission, Auxiliary Transmission, Brake Saver Oil.
Procedure: (see Figure 5-4 on page 5-10.)
Note: To check the programming of the warning LED in the Main Transmission
Temperature gauge, go to Section 6.5 on page 6-8.
1. With the ignition off, disconnect the 2-wire connector from the appropriate tem-
perature sender.
2. Connect a 1% resistor across the connector pins (see the following table for the
value):
If your gauge
scale reads:
Use this resistor
value:
The gauge should
read:
100° F TO 300°
F
392 ohms
47.5 ohms
About 100° F
About 300° F
100° F to 350° F 392 ohms
28 ohms
About 100° F
About 350° F
Note - Using values other than those in the table will cause incorrect gauge readings.
3. Switch the ignition on. After the initialization, the gauge should read as indicated
in the table. Repeat these steps for both resistor values indicated.
a. If the gauge reading is correct, replace the appropriate sender unit.
b. If the gauge reading is incorrect, connect the HDT to the private data bus
and compare its reading to the suspect gauge’s reading. If the readings
are about the same, replace the Interface Module; otherwise, replace the
gauge.
c. If the gauge does not respond at all, go to the next step.
4. Check the wiring between the 2-wire sensor connector and the 10-pin Interface
Module connector J3 as follows:
a. Switch the ignition off.
b. Unplug J3 from the Interface Module.
c. Place a jumper from one pin of the 2-wire sensor connector to the other.
Model 387 Instrument System Service Manual
072-40245 B 5-9 Troubleshooting Procedures
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