Circuit Description; Diagnostic Aids - Isuzu 2000 Trooper Workshop Manual

Circuit Description

The shift lamp indicates the best transmission shift point
for maximum fuel economy.
The lamp is controlled by the Power Train Control Module
(PCM) and is turned "ON" by grounding the BLK wire.
The PCM is used information from the following inputs to
control the upshift lamp.
D Engine Coolant temperature (ECT) Sensor
D Throttle Position Sensor
D Vehicle Speed Sensor
D Engine Speed
The PCM uses the measured RPM and the vehicle speed
to calculate what gear the vehicle is in.
It's this calculation that determines when the upshift lamp
should be turned "ON".

Diagnostic Aids

An intermittent may be caused by a poor connection,
rubbed-through wire insulation.
connections or a damaged harness.
Step
1 1. Verify the customer complaints in accordance with
mentioned below: Go to the adequate Step Chart
first.
D
At the 1
illuminate: Go to Step Chart
D
At the 3
illuminate: Go to Step Chart
D
Upshift Lamp doesn't illuminate always.
2. Ignition "ON", engine "OFF".
3. Using the Tech 2, check to see if the upshift lamp
turn "ON" or "OFF".
Does the upshift lamp stay "OFF"?
2 Check for an open of 15A Turn Backup Fuse.
Was a problem found?
3 Replace the fuse.
Is the action complete?
4 Check for an burned out the Upshift Lamp.
Was a problem found?
5 Replace the Upshift Lamp.
Is the action complete?
6 1. Check for an Clutch Switch operation and the fixing
condition.
2. Check for an open or short of clutch switch.
3. Check for an open or short of WHT/GRN wiring
harness between Turn Backup Fuse and Clutch
Switch.
Was a problem found?
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Check for poor
Up-Shift Lamp System Check
Action
st gear position, the lamp doesn't
gear position, the lamp doesn't
rd
Inspect the PCM harness and connector for proper
mating, broken locks, improperly formed or damaged
terminals, poor terminal-to-wire
damaged harness.
Test Description
1. This should not turn "ON" the up-shift lamp. If the
lamp is "ON", there is a short to ground in BLK or a
fault PCM.
2. This checks the upshift lamp circuit up to the PCM
connector.
If the up-shift lamp illuminates, then the PCM
connector is faulty or PCM does not have the ability
to ground the circuit.
Value(s)
— Go to Step 2
— Go to Step 3
Verify Repair
Go to Step 5
—
Verify Repair
— Go to Step 7
6E–127
connection and
Yes No
Go to Step 12
Go to Step 4
Refer to Sec-
tion 8
— —
Go to Step 6
— —
Go to Step 8