does anyone know how to reset the actual temp setting on the over-head display? Something happened and it went haywire. It is now 130 deg outside and doesn't change from that. The compas is still right and everything else up there seems to work fine but not the temp setting. Thanks guys!

 

SENSOR-AMBIENT AIR TEMPERATURE
DESCRIPTION
The ambient temperature sensor is a variable resistor mounted to a bracket that is secured with a screw to the left side of the radiator yoke, behind the radiator grille and in front of the engine compartment.
The ambient temperature sensor cannot be adjusted or repaired and, if inoperative or damaged, it must be replaced.

OPERATION
The ambient temperature sensor is a variable resistor that operates on a five-volt reference signal sent by the Front Control Module (FCM). The resistance in the sensor changes as temperature changes, changing the temperature sensor signal circuit voltage to the FCM. Based upon the resistance in the sensor, the FCM senses a specific volt- age on the temperature sensor signal circuit. The FCM then translates the voltage into a temperature reading that it sent over the Programmable Communications Interface (PCI) data bus circuit to other modules utilizing temper- ature information.

DIAGNOSIS AND TESTING
AMBIENT TEMPERATURE SENSOR
The temperature function is supported by the ambient temperature sensor, a wiring circuit, and Front Control Module (FCM). If any portion of the ambient temperature sensor circuit fails or if Programmable Communications Interface (PCI) Data Bus information is missing, a (– –) will appear in the display in place of the temperature. When the
8M - 38 OVERHEAD CONSOLE - SERVICE INFORMATION DR/DH
sensor is exposed to temperatures above 55° C (130° F), or if the sensor circuit is shorted, 55° C (130° F) will appear in the display in place of the temperature, when the sensor is exposed to temperatures below - 40° C (- 40° F) or if the sensor circuit is open, - 40° C (- 40° F) will appear in the display.
The ambient temperature sensor circuit can also be diagnosed using the following Sensor Test, and Sensor Circuit Test. If the temperature sensor and circuit are confirmed to be OK, but the temperature display is inoperative or incorrect, test the compass mini-trip computer (

SENSOR TEST
1. Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Disconnect the ambient temperature sensor harness connector.
2. Measure the resistance of the ambient temperature sensor. At - 40° C (- 40° F), the sensor resistance is 336 kilohms. At 55° C (130° F), the sensor resistance is 2.488 kilohms. The sensor resistance should read between these two values. If OK, refer to Sensor Circuit Test in this group. If not OK, replace the inoperative ambient temperature sensor.

SENSOR CIRCUIT TEST
For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wir- ing diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.
1. Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Disconnect the wire harness connectors from the ambient temperature sensor and the FCM.
2. Connect a jumper wire between the two terminals in the body half of the ambient temperature sensor harness connector.
3. Check for continuity between the sensor return circuit and the ambient temperature sensor signal circuit cavities of the FCM harness connector. There should be continuity. If OK, go to Step 4. If not OK, repair the open sensor return circuit or ambient temperature sensor signal circuit to the ambient temperature sensor as required.
4. Check for continuity between the ambient temperature sensor signal circuit cavity of the FCM harness connector and a good ground. There should be no continuity. If OK, test the compass mini-trip computer operation, (Refer to 8 - ELECTRICAL/OVERHEAD CONSOLE/COMPASS/MINI-TRIP COMPUTER - DIAGNOSIS AND TESTING). If not OK, repair the shorted ambient temperature sensor signal circuit as required.

REMOVAL
1. Open the hood. 2. Disconnect and isolate the battery negative cable. 3. Working on the underside of the hood, remove screw holding sensor to hood panel. 4. Disconnect the sensor electrical connector and remove sensor from vehicle.

INSTALLATION
1. Connect the sensor electrical connector. 2. Working on the underside of the hood, install screw holding sensor to hood panel. 3. Connect the battery negative cable. 4. Close the hood.

 

I guess the key line is...

The ambient temperature sensor cannot be adjusted or repaired and, if inoperative or damaged, it must be replaced.

 

Part number 56042395

Looks like a $50 sensor

 

I'm suspecting my battery is on it's way out. The neg terminal is loose which is probably why it shorted out in the first place.

 

you truck would show other problems if the battery was on its way out or low voltage. (not just the ambient air temp sensor)

when the display reads 130 the ambient temp sensor is open (not completely poss.)

so there is either an open wire, disconnected sensor or totally failed sensor.
inspect the sensor and find out.
its connected to your drivers side lower bolt of the headlight

 

Good job from the service manual. I was going to post the same thing