Circuit Description
With the engine running and the transmission in Drive 4, the Sport Mode Indicator Lamp should transition from On to Off or from Off to On with each press of the Sport Mode Selector Switch. The ignition voltage is supplied directly to the indicator bulb. The transmission control module (TCM) controls the lamp by grounding the control circuit via an internal solid state device called a driver. The Sport Mode Selector Switch signal circuit is pulled up to B+ within the TCM. The other side of the switch connects to ground. When the switch is on, the signal voltage is pulled low. The TCM interprets this as sport mode requested. The Sport Mode selection causes the TCM to use a more aggressive shift schedule for improving performance and providing a more positive shift feel.
Vehicles equipped with Fuel Cap Lamps utilize the Sport Mode lamp to indicate a transmission malfunction. In these vehicles, the Sport Mode Lamp flashes at 200 millisecond intervals when the TCM commands the lamp ON.
Vehicles not equipped with Fuel Cap Lamps are equipped with a dedicated Service Transmission Lamp (STL) on the Instrument Panel Cluster (IPC). The STL illuminates steadily when the TCM commands the lamp ON.
Diagnostic Aids
An intermittent may be caused by the following:
| • | Corrosion |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
Refer to Symptoms in Engine Controls for intermittents.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the On-Board Diagnostic System Check performed? | -- | ||||||||
2 | Any DTCs that are set must be corrected before performing this diagnostic procedure. Are there any DTCs set? | -- | Go to the applicable DTCs | |||||||
3 |
Does the Sport Mode indicator lamp turn ON and OFF? | -- | System OK | |||||||
4 |
Does the display change back and forth between On and Off? | -- | ||||||||
5 | Use the Scan Tool in order to command the Sport Mode indicator lamp On and Off. Does the lamp go On and Off? | -- | ||||||||
6 | Is the lamp always on? | -- | ||||||||
Do the other indicator lamps in the instrument panel operate? | -- | |||||||||
8 |
Is the lamp On? | -- | ||||||||
9 | Check the Sport Mode Indicator Lamp circuit for the following conditions:
Refer to General Electrical Diagnosis in Wiring Systems. Is the action complete? | -- | -- | |||||||
10 |
Does the lamp illuminate? | -- | ||||||||
11 | Does the display always indicate On? | -- | ||||||||
12 |
Does the state change each time the jumper is momentarily connected? | -- | ||||||||
13 |
Is the continuity indicated? | -- | ||||||||
14 | Use a fused jumper wire in order to connect the Sport Mode selector switch signal circuit terminal 2 to ground in the switch harness connector, while observing the Scan Tool . Does the display indicate On? | -- | ||||||||
15 |
Is the resistance within the specified range? | 0-5ohms | ||||||||
16 | Repair the short to ground in the lamp control circuit. Is the action complete? | -- | -- | |||||||
17 | Repair the feed circuit to the instrument panel indicator lamps. Is the action complete? | -- | -- | |||||||
18 | Repair the signal circuit shorted to ground. Is the action complete? | -- | -- | |||||||
19 | Repair the open/high resistance signal circuit. Is the action complete? | -- | -- | |||||||
20 | Check the ground circuit to the Sport Mode switch for an open or a high resistance condition. Was a condition found and corrected? | -- | ||||||||
21 | Replace the Sport Mode switch. Is the action complete? | -- | -- | |||||||
22 | Check the TCM harness connector for a poor connection or poor terminal tension. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found and corrected? | -- | ||||||||
23 | Replace the TCM. Refer to Transmission Control Module Replacement . Is the action complete? | -- | -- | |||||||
24 |
Caution: Apply the parking brake and block the drive wheels before performing this procedure in order to prevent bodily injury. Does the Sport Mode lamp correspond to the operation of the switch? | -- | System OK |
