For 1990-2009 cars
Engine Controls Components
Ignition Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Diagnostic Aids

For diagnosis of the instrument panel, perform the System Check in the Instrument Panel Cluster (IPC) Microprocessor.

Check for the following conditions:

• | Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

• | Damaged harness. Inspect the wiring harness for damage.

### Test Description

The number below refers to the step number on the Diagnostic Table:

1. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

#### Tachometer Control Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any DTCs set? | -- | Go to Applicable DTC | Go to Step 3
3 | Install scan tool, monitor engine RPM. Does scan tool engine RPM indicate approximate engine operation? | -- | Go to Step 4 | Go to Step 5
4 | Monitor the Tachometer output on the Instrument Panel Cluster with engine RPM on scan tool. Do they closely match each other? | -- | Go to Step 9 | Go to Step 5
5 | Refer to Data Link Connector Diagnosis for diagnosing Serial Data circuit. Was a problem found? | -- | Go to Step 9 | Go to Step 6
6 | Refer to Instrument Cluster System Check in Instrument Panel, Gauges and Console to diagnose the Tachometer. Was a problem found? | -- | Go to Step 9 | Go to Step 7
7 | Install scan tool to known good vehicle and monitor engine RPM. Does engine RPM on scan tool indicate approximate engine operation? | -- | Go to Step 8 | Go to Scan Tool Does Not Communicate with Components in Wiring System
8 | Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Step 9 | --
9 | Check for proper operation of the Tachometer. Refer to Instrument Cluster System Check in Instrument Panel, Gauges and Console. Is the correct operation indicated? | -- | System OK | Go to Step 2