Tachometer Does Not Operate: 2.2 L Engine
Step
| Action
| Value(s)
| Yes
| No
|
DEFINITION: The Tachometer on the Instrument
Cluster does not indicate engine RPM with the engine running. Alternatively,
it may indicate RPM with the engine stopped or it may indicate an excessively
high RPM. The engine operates without other ignition related symptoms.
|
1
|
- Start the engine.
- Vary the engine speed.
- Observe the Tachometer indication on the Instrument Cluster.
- Place the Ignition Switch in the Off position.
Does the Tachometer indicate a varying engine speed?
| --
| Go to
Step 11
| Go
to
Step 2
|
2
|
- Disconnect Connector C2 at the Powertrain Control Module.
- Using an ohmmeter, measure the resistance between Powertrain Control
Module Connector C2 Cavity 10 for the WHT (121) wire and ground.
Is the resistance to ground less than 1.2 ohms?
| 1.2 ohms
| Go to
Step 3
| Go
to
Step 6
|
3
|
- Disconnect the Instrument Cluster.
- Using an ohmmeter, measure the resistance between Instrument Cluster
Pins 8 and 11.
Is the resistance to ground less than 1.2 ohms?
| 1.2 ohms
| Go to
Step 5
| Go
to
Step 4
|
4
|
- Locate and repair the short to ground on the WHT (121) wire between
the Powertrain Control Module and the Instrument Cluster.
- Reconnect Connector C2 at the Powertrain Control Module.
- Reconnect the Instrument Cluster.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
5
|
- Replace the Instrument Cluster.
- Reconnect Connector C2 at the Powertrain Control Module.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
6
|
- Disconnect the Instrument Cluster.
- Connect a self-powered test lamp between Instrument Cluster connector
Cavity 8 and Powertrain Control Module Connector C2 Cavity 10 for the WHT
(121) wire.
Does the test lamp light?
| --
| Go
to
Step 8
| Go to
Step 7
|
7
|
- Locate and repair the open circuit in the WHT (121) wire between
the Powertrain Control Module and the Instrument Cluster.
- Reconnect the Instrument Cluster.
- Reconnect Connector C2 at the Powertrain Control Module.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
8
|
- Reconnect Connector C2 at the Powertrain Control Module.
- Reconnect the Instrument Cluster.
- By back-probing the terminal, connect a voltmeter between Instrument
Cluster connector Cavity 8 for the WHT (121) wire and ground.
- Start the engine.
- Observe the voltage indication.
- Place the Ignition Switch in the Off position.
Was signal voltage present on the WHT (121) wire?
| --
| Go to
Step 9
| Go
to
Step 10
|
9
| Replace the Instrument Cluster.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
10
| Replace
the Powertrain Control Module. Refer to
Powertrain Control Module Replacement/Programming
in
Engine Controls -- 2.2L.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
11
|
- Connect a scan tool to the Data Link Connector.
- Start the engine.
- Monitor the engine speed with the scan tool.
- Monitor the Tachometer indication on the Instrument Cluster.
- Compare the two indications.
Is the Tachometer indication on the Instrument Cluster within 100 RPM
of the actual engine speed?
| 100 RPM
| Go
to
Engine Electrical Diagnostic System Check
.
| Go to
Step 12
|
12
|
- Observe the engine speed on the scan tool.
- Connect a Digital Multimeter with counting capability by backprobing
In-Line Connector C102 Cavity A for the WHT (121) wire.
- Connect the other lead to ground.
- Measure the engine speed output from the Powertrain Control Module
on the WHT (121) wire.
- Monitor the engine speed indicated by the scan tool.
- Observe if the two engine speed indications are within 100 RPM
of each other with the engine idling.
Does the Powertrain Control Module produce an accurate engine speed
output?
| 100 RPM
| Go to
Step 14
| Go to
Step 13
|
13
| Replace the Powertrain
Control Module. Refer to
Powertrain Control Module Replacement/Programming
in
Engine Controls -- 2.2L.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
14
| Replace
the Instrument Cluster.
Are the repairs complete?
| --
| Go
to
Engine Electrical Diagnostic System Check
.
| --
|
