Raider 4WD V6-3.7L SOHC (2007)
Overdrive Indicator Lamp: Description and Operation
TOW/HAUL INDICATOR
DESCRIPTION
A tow/haul indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional overdrive automatic
transmission, this indicator is electronically disabled. The tow/haul indicator is located below the minor gauge set on the left side of the cluster.
The tow/haul indicator consists of a stencil-like cut-out of the text TOW/HAUL in the opaque layer of the instrument cluster overlay. The dark outer
layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. An amber Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the indicator to appear in amber through the translucent outer layer of the overlay when it is illuminated from
behind by the LED, which is soldered onto the instrument cluster electronic circuit board.
When the exterior lighting is turned ON, the illumination intensity of the tow/haul indicator is damnable, which is adjusted along with the cluster general
illumination lighting using the panel lamps dimmer thumb wheel on the headlamp switch. The tow/haul indicator is serviced as a unit with the instrument
cluster.
OPERATION
The tow/haul indicator gives an indication to the vehicle operator when the tow/haul function of the tow/ haul switch has been selected, revising the shift
schedule of the electronically controlled automatic transmission. This indicator is controlled by a transistor on the instrument cluster circuit board based
upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Controller Area
Network (CAN) data bus.
The tow/haul indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this
indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED
will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by
the instrument cluster transistor. The instrument cluster will turn ON the tow/haul indicator for the following reasons:
-
Tow/Haul Indicator Lamp-On Message - Each time the cluster receives an electronic tow/haul indicator lamp-ON message from the PCM
indicating that the tow/haul shift schedule has been selected, the indicator will be illuminated. The indicator remains illuminated until the cluster
receives a lamp-OFF message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first.
-
Actuator Test - Each time the cluster is put through the actuator test, the tow/haul indicator will be turned ON, then OFF again during the bulb
check portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The PCM continually monitors the tow/haul switch to determine the proper outputs to the automatic transmission. The PCM then sends the proper
lamp-ON or lamp-OFF message to the Electromechanicall Instrument Cluster (EMIC). For further diagnosis of the tow/haul indicator or the instrument
cluster circuitry that controls the LED, Refer to Instrument Cluster Testing.
For proper diagnosis of the transmission control system, the PCM, the EMIC, the CAN data bus or the electronic communication related to tow/haul
indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
