TB - Testing Notes

DESCRIPTION
The 4x4 Low Switch is an input used by the Powertrain Control Module (PCM), which, when closed, allows the use of a secondary shift schedule while in the low range.

The Transmission Control Switch (TCS) allows the vehicle operator to disengage the overdrive feature when desired.

The Transmission Control Indicator Light (TCIL) informs the vehicle operator of the Overdrive Range Status "ON" or "OFF" and also informs the operator of certain transmission sensor/actuator malfunctions by flashing the TCIL.



NOTE
You should enter this Pinpoint Test only when you have been directed here from Diagnostic Routines.

REMEMBER
This Pinpoint Test is not intended to diagnose components in the transmission. To prevent the replacement of good components, be aware that the following non-Electronic Engine Controls (EEC) areas may be at fault:

- Engine
- Performance
- Vacuum
- Cooling

- Electrical
- Charging system

- Transmission
- Hydraulic fluid, friction elements, cooling
- Transfer case linkage
- Transfer case internal damage

This Pinpoint Test is intended to diagnose only the following:

- Harness Circuits: 4x4 LOW, TCIL, TCS.

- PCM.