1994 PCED OBDI-A | SECTION 6A: EEC-IV Pinpoint Test
Procedures |
DJ1 CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODE (DTC) 14: ERRATIC ENGINE RPM SIGNAL
Note: To prevent the replacement of good components, verify proper Engine RPM sensor installation and complete electrical connection.
DTC 14 indicates the engine rpm signal output was missing pulses while the engine was running.
- Check EEC system harness for:
- Loose wires/connectors.
- On board transmitter (two-way radio).
- On board telephone, etc.
- Verify installations have been performed according to manufacturer's instructions and specifications regarding routing of antenna and wire leads.
- Key off.
- Enter Engine Running Continuous Monitor Diagnostic Test Mode (DTM). Refer to Quick Test Appendix, Section 5A.
- Observe VOM or STAR LED for indication of a fault while performing the following:
- Lightly tap on the Engine RPM sensor.
- Wiggle the Engine RPM sensor connector.
Note: Continuous Monitor DTM may exit when a fault is indicated. Reenter Continuous Monitor DTM to continue diagnosis.
Is a fault indicated?
| Yes | No |
|---|
| SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A). RERUN Quick Test. | GO to DJ2. |
DJ2 CHECK EEC VEHICLE HARNESS
- While still in Continuous Monitor DTM from DJ1, observe VOM or STAR LED for a fault indication while performing the following:
- Grasp the vehicle harness close to the Engine RPM sensor. Wiggle shake or bend a small section at a time while working toward the dash panel and the PCM. Isolate the engine rpm circuit for this test.
Is a fault indicated?
| Yes | No |
|---|
| ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A). RERUN Quick Test. | GO to DJ3. |
DJ3 CHECK CONTINUITY OF ENGINE RPM
SENSOR VEHICLE HARNESS CIRCUITS
- Key off.
- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box, leave PCM disconnected.
- Disconnect Engine RPM sensor.
- Measure resistance between Test Pin 4 at the breakout box and RPM(+) circuit at the Engine RPM sensor vehicle harness connector.
- Measure resistance between Test Pin 44 at the breakout box and RPM(-) circuit at the Engine RPM sensor vehicle harness connector.
Is each resistance less than 5.0 ohms?
| Yes | No |
|---|
| GO to DJ4. | SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
DJ4 CHECK ENGINE RPM SENSOR VEHICLE HARNESS CIRCUITS FOR SHORTS TO POWER OR GROUND
- Key off.
- Breakout box installed, PCM disconnected.
- Engine RPM sensor disconnected.
- Measure resistance between Test Pin 4 and Test Pins 37/57, 40, and 44 at the breakout box.
- Measure resistance between Test Pin 44 and Test Pins 37/57 at the breakout box.
Is each resistance greater than 10,000 ohms?
| Yes | No |
|---|
| GO to DJ5. | SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
DJ5 CHECK ENGINE RPM SENSOR RESISTANCE
- Key off.
- Engine RPM sensor disconnected.
- Measure resistance between Engine RPM sensor terminals at the RPM sensor.
Is the resistance between 2400 and 2800 ohms?
| Yes | No |
|---|
| REPLACE PCM. REMOVE breakout box. RECONNECT Engine RPM sensor. RERUN Quick Test. | REPLACE RPM sensor. REMOVE breakout box. RECONNECT all components. |
DJ: Introduction