1. Start the engine.
2. Observe the instrument cluster tachometer.
3. Turn the engine OFF.

Did the instrument cluster tachometer operate?

--

Go to Step 10

Go to Step 2

Inspect the ECM I fuse in the instrument panel (IP) fuse block.

Is the fuse open?

--

Go to Step 3

Go to Step 4

Locate and repair the source of the overload in CKT 439 (PNK) between the IP fuse block and the instrument cluster connector.

Is the repair complete?

--

System OK

--

Inspect the condition of G 108.

Is it clean and tight?

--

Go to Step 6

Go to Step 5

Repair G 108 as necessary.

Is the repair complete?

--

System OK

--

1. Disconnect the instrument cluster .
2. Turn the ignition to the RUN position.
3. Connect a test light from the instrument cluster connector, cavity 7 to ground. Refer to Using Connector Test Adapters in Wiring Systems.

Did the test light illuminate?

--

Go to Step 8

Go to Step 7

Locate and repair the open in CKT 439 (PNK) between the IP fuse block and the instrument cluster connector.

Is the repair complete?

--

System OK

--

Connect a test light from the instrument cluster connector, cavity 4 to B +.

Did the test light illuminate?

--

Go to Step 10

Go to Step 9

Locate and repair the open in CKT 451 (BLK/WHT) between the instrument cluster connector and G 108.

Is the repair complete?

--

System OK

--

1. Turn the ignition to the OFF position.
2. Disconnect the ignition coil for gasoline engines, or the generator for diesel engines.
3. Inspect CKT 121 (WHT) between the instrument cluster connector, cavity 6 and the ignition coil connector, cavity B (gasoline) , or the generator connector, cavity P (Diesel) for the following conditions:

•

An open

•	Poor connections

•	Any indications of high resistance

•	A short to ground

•	A short to battery voltage

Does a short, open, poor connection, or high resistance condition exist in CKT 121 (WHT)?

--

Go to Step 11

Go to Step 12

Repair any condition found in CKT 121 (WHT).

Is the repair complete?

--

System OK

--

1. Connect the generator on diesel engines, or the ignition coil on gasoline engines.
2. Start the engine.
3. Use a J 39200 DMM to measure the voltage from the instrument cluster connector, cavity 6 to ground.
4. Observe the J 39200 for potentially pulsating voltage at or below 14 volts.
5. Turn the engine OFF.

Was there voltage at cavity 6 of the instrument cluster connector?

--

Go to Step 13

Go to Step 15

1. Start the engine.
2. Install a Scan Tool .
3. Select the Engine Speed display on the scan tool.
4. Observe the engine speed displayed by the scan tool and the revolutions per minute (RPM) indicated by the instrument cluster tachometer.

Is the instrument cluster tachometer within specifications?

250 RPM

System OK

Go to Step 14

Replace the instrument cluster.

Is the repair complete?

--

System OK

--

Replace the generator on diesel engines, Refer to Generator Replacement in Engine Electrical, or replace the ignition coil on gasoline engines, Refer to Ignition Coil and Ignition Coil Module Replacement in Engine Electrical.

Is the repair complete?

--

System OK

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