1994 PCED OBDI-A | SECTION 6A: EEC-IV Pinpoint Test
Procedures |
TF: Turbine Shaft Speed Sensor (TSS)/Output Shaft Speed Sensor (OSS) |  TF: Introduction |
TF1 ENGINE RUNNING DIAGNOSTIC TROUBLE CODE (DTC) 639: CHECK TSS/OSS HARNESS CONNECTOR CONTINUITY
DTC 639 indicates frequency or voltage of the TSS/OSS is insufficient to the Powertrain Control Module (PCM).
Possible causes:
- Open circuit in harness.
- Short circuit in harness.
- Damaged TSS/OSS.
- Damaged PCM.
- Key off.
- Disconnect TSS/OSS.
- 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.
- Measure resistance between Test Pin 5 at the breakout box and TSS+/OSS+ circuit at TSS/OSS vehicle harness connector.
- Measure resistance between Test Pin 46 at the breakout box and SIG RTN circuit at the TSS vehicle harness connector.
- For 5.0L E-Series:
- Also measure resistance between Test Pin 29 at the breakout box and SIG RTN circuit at the TSS vehicle harness connector.
Is each resistance less than 5.0 ohms?
| Yes | No |
|---|
| GO to TF2. | SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
TF2 CHECK TSS+/OSS+ CIRCUIT FOR SHORT TO POWER OR GROUND
Is each resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REMOVE breakout box. RECONNECT PCM. GO to TF3. | SERVICE short circuit(s). REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
TF3 CHECK TSS/OSS RESISTANCE
- Key off.
- TSS/OSS disconnected.
- Measure resistance of TSS/OSS sensor.
- For AX4S Transmission:
- Is resistance between 100 and 200 ohms?
- For AODE/4R70W Transmission:
- Is resistance between 450 and 750 ohms?
- For CD4E Transmission:
- Is resistance between 149 and 290 ohms?
| Yes | No |
|---|
| GO to Transmission Group in Service Manual to verify internal components. If OK, then replace PCM. REMOVE breakout box. RERUN Quick Test. | REPLACE TSS. REMOVE breakout box. RERUN Quick Test. |
TF10 ENGINE RUNNING DTC 639:
CHECK TSS RESISTANCE
Engine Running DTC 639 indicates an error has been detected in the Transmission Speed Sensor (TSS) input signal.
Possible causes:
- Open or shorted harness.
- Damaged transmission speed sensor.
- Damaged Powertrain Control Module (PCM).
- Key off.
- Disconnect transmission connector (12 pin at transmission).
- Measure resistance between TSS(+) and TSS(-) pins at transmission 12 pin connector.
Is resistance between 200 and 600 ohms?
| Yes | No |
|---|
| GO to TF11. | INSPECT transmission wiring for opens/shorts. If OK, REPLACE transmission speed sensor. RERUN Quick Test. |
TF11 CHECK TSS CIRCUITS FOR SHORT TO POWER
- Key off.
- Transmission 12 pin connector disconnected.
- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Key on.
- Measure voltage between TSS (+) circuit at the transmission 12 pin vehicle harness connector and chassis ground.
- Measure voltage between TSS(-) circuit at the transmission 12 pin vehicle harness connector and chassis ground.
Are both voltages less than 0.5 volt?
| Yes | No |
|---|
| Key off. GO to TF12. | SERVICE short circuit. RECONNECT all components. RERUN Quick Test. |
TF12 CHECK TSS CIRCUITS FOR SHORT TO GROUND OR EACH OTHER
- Key off.
- Transmission 12 pin connector disconnected.
- PCM disconnected.
- Measure resistance between TSS (+) circuit at transmission 12 pin vehicle harness connector and chassis ground.
- Measure resistance between TSS(-) circuit at transmission 12 pin vehicle harness connector and chassis ground.
- Measure resistance between TSS (+) and TSS(-) circuits at transmission 12 pin vehicle harness connector.
Are all resistances greater than 10,000 ohms?
| Yes | No |
|---|
| GO to TF13. | SERVICE short circuit. RECONNECT all components. RERUN Quick Test. |
TF13 CHECK TSS CIRCUIT CONTINUITY
- Key off.
- Transmission 12 pin connector disconnected.
- Install breakout box or 4EAT tester. Leave PCM disconnected.
- Measure resistance between Test Pin 24 and TSS (+) circuit at transmission 12 pin vehicle harness connector.
- Measure resistance between Test Pin 44 and TSS(-) circuit at transmission 12 pin vehicle harness connector.
Are both resistances less than 5.0 ohms?
| Yes | No |
|---|
| GO to TF14. | SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
TF14 CHECK PCM FOR INTERNAL SHORTS
- Key off.
- Breakout box installed.
- Connect PCM to breakout box.
- Transmission 12 pin connector disconnected.
- Measure resistance between Test Pin 24 and Test Pins 44, 37, 57, 40 and 60.
Is each resistance greater than 500 ohms?
| Yes | No |
|---|
| GO to TF15. | REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. |
TF15 CHECK TSS OUTPUT
- Key off.
- PCM connected to breakout box.
- Reconnect transmission 12 pin connector.
- DVOM on AC scale (to monitor less than 5.0 volts AC).
- Start engine.
- Measure voltage between Test Pins 24 and 44 at breakout box while varying engine rpm.
Does AC voltage vary greater than 0.5 volt?
| Yes | No |
|---|
| REPLACE PCM. REMOVE breakout box. RERUN Quick Test. | REPLACE TSS. REMOVE breakout box. RERUN Quick Test. |
TF90 CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODE (DTC) 639: COMPLETE TRANSMISSION DRIVE CYCLE, VERIFY DTC
Continuous Memory DTC 639 indicates that sometime during the last 40 or 80 warm-up cycles, the PCM detected an error in the TSS/OSS output signal.
Possible causes:
- Transmission (internal components).
- Damaged TSS/OSS.
- Damaged harness circuits.
- Damaged PCM.
- Perform transmission Drive Cycle:
- TRANSMISSION DRIVE CYCLE:
- Record and clear Continuous Memory DTCs.
- Warm engine to operating temperature.
- Place gear selector in DRIVE.
- Obey all local traffic laws. Accelerate heavily to 35 mph.
- Return to idle.
- Shut the engine off.
- After drive cycle is completed, run Key On Engine Off Self-Test and record Continuous Memory DTCs displayed.
Did Continuous Memory DTC 639 repeat?
| Yes | No |
|---|
| GO to TF91. | Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to Section 7A. For all others, CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A). |
TF91 CHECK TSS/OSS CIRCUIT CONTINUITY
- Key off.
- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box, PCM disconnected.
- Disconnect TSS/OSS.
- Measure resistance between Test Pin 5 at breakout box and TSS/OSS circuit at sensor vehicle harness connector.
- Measure resistance between Test Pin 46 at breakout box and SIG RTN at the TSS/OSS vehicle harness connector.
- For 5.0L E-Series:
- Also measure resistance between Test Pin 29 at the breakout box and SIG RTN circuit at the TSS/OSS vehicle harness connector.
Is each resistance less than 5.0 ohms?
| Yes | No |
|---|
| GO to TF92. | SERVICE open circuit. REMOVE breakout box. RECONNECT all components. REPEAT Test Step TF90 to verify elimination of DTC. |
TF92 CHECK TSS/OSS CIRCUITS FOR SHORT TO POWER OR GROUND
- Key off.
- TSS disconnected.
- Breakout box installed, PCM disconnected.
- Measure resistance between Test Pin 5 and Test Pin 37/57 at breakout box.
- Measure resistance between Test Pin 5 and Test Pins 40/60 and 46 at breakout box.
Is each resistance greater than 500 ohms?
| Yes | No |
|---|
| GO to TF93. | SERVICE short circuit. REMOVE breakout box. RECONNECT all components. REPEAT Test Step TF90 to verify elimination of DTC. |
TF93 CHECK TSS/OSS RESISTANCE
- Key off.
- TSS disconnected.
- Measure resistance of TSS/OSS.
- For CD4E Transmission TSS:
- Is the resistance between 149 and 290 ohms?
- For AODE/4R70W Transmission OSS:
- Is the resistance between 450 and 750 ohms?
- For AX4S/AX4N Transmission TSS:
- Is the resistance between 100 and 200 ohms?
| Yes | No |
|---|
| GO to Transmission Group in Service Manual to verify internal components. If OK, then replace PCM. REMOVE breakout box. RECONNECT TSS. REPEAT Test Step TF90 to verify elimination of DTC. | REPLACE TSS/OSS. REMOVE breakout box. REPEAT Test Step TF90 to verify elimination of DTC. |
TF95 CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODE (DTC) 639: CHECK TSS WIRING
Continuous Memory DTC 639 indicates that sometime during the last 80 warm-up cycles an error was detected in the Transmission Speed Sensor (TSS) input signal.
Possible causes:
- Intermittent open or shorted harness.
- Intermittent fault in TSS.
- Transmission fluid drained and refilled (if, within one minute of the first start after a transmission fluid change, the vehicle is put in gear, a Continuous Memory DTC 639 could be set due to an insufficient time for the new transmission fluid to fill all the cavities).
- Key off.
- Visually check the TSS wires for obvious concerns. Service as necessary.
- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box. Connect PCM to breakout box.
- DVOM to 20 volts scale.
- Connect DVOM between Test Pin 24 and Test Pin 44 at breakout box.
- Start engine.
- Observe DVOM for a fault indication while performing the following (the voltage should remain stable. A fault will be indicated by the voltage becoming erratic or dropping to zero):
CAUTION: While performing this Diagnostic Test Mode (DTM), use caution not to touch any moving engine parts.
- Shake, wiggle, bend the TSS (+) and TSS(-) circuits from the transmission to the PCM.
- Lightly shake and tap the transmission connector, EEC-IV connector and other related harness connectors.
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. | Key off. GO to TF96. |
TF96 CHECK PCM AND HARNESS CONNECTORS
- Key off.
- Disconnect the transmission 12 pin connector and all other connectors related to the TSS one at a time. Inspect the connectors for damaged or pushed out pins, corrosion, loose wires, etc. Reconnect each connector after inspection.
Are connectors and terminals OK?
| Yes | No |
|---|
| For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to Section 7A. If an EEC-IV monitor box or Scan Tool is not available, GO to TF97. | SERVICE as necessary. RECONNECT all connectors/ components. RERUN Quick Test. |
TF97 ROAD TEST (ESCORT/TRACER ONLY)
The purpose of the road test is to identify an area of concern by monitoring certain controlled parameters while trying to recreate a driveability or MIL symptom.
Note: A basic working knowledge of the EEC-IV system is critical to effectively analyze road test data.
WARNING: THIS ROAD TEST IS A SUGGESTED BUT OPTIONAL PROCEDURE. ALL APPLICABLE SAFETY PROCEDURES AND TRAFFIC LAWS MUST BE FOLLOWED. IN ORDER FOR A ROAD TEST TO BE PERFORMED IT IS REQUIRED THAT ANOTHER PERSON ACCOMPANY THE DRIVER. THE ACCOMPANYING PERSON CAN MAKE MEASUREMENTS, OBSERVE CHANGES AND RECORD NOTES. IF FOR SOME REASON THIS TEST IS NOT PERFORMED, RETURN TO SECTION 2A FOR OTHER POSSIBLE CAUSES.
Prepare Vehicle For a Road Test
- Disconnect Powertrain Control Module (PCM) connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box/4EAT tester and reconnect PCM to breakout box/4EAT tester.
- Other materials needed: DVOM, pencil, paper, appropriate schematic/pin usage sheet (from Section 3A or Section 4A).
- Optional equipment:
- Fuel pressure gauge, manifold vacuum gauge, MAP/BARO tester.
- Preliminary Power/Ground Checks
- With the key ON and a DVOM referenced to the battery negative post, check the following signals for correct values.
- POWERS: KAPWR > 10.5V (Pin 1), VPWR > 10.5V (Pins 37/57), VREF 5 ± 1V (Pin 26).
GROUNDS: (all = 0 ± .5V): PWR GND (Pins 40/60), SIG RTN (Pin 46), IGN GND (Pin 16).
OPTIONAL GROUNDS: HO2S GND (Pin 49), CSE GND (Pin 20) MAF RTN. (Pin 9 or 15).
- Obtaining Other Information and Materials Before the RoadTest
- Refer to the Symptom Charts in Section 7A, EEC-IV Monitor Box: Intermittent Fault Diagnosis chart that most resemble the driveability or MIL symptom. Before the road test, perform the Visual/Mechanical Checks that are listed. Next, list the EEC-IV sensors and actuators in the order given. These are the main signals that will be monitored.
- Refer to the proper Diagnostic Reference Value Sheet in Section 7A, Appendix. Although these charts were designed for use with the EEC-IV Monitor Box, most of the values can be read using the breakout box and a DVOM (with the DVOM referenced to ground, all values in DCV units can be used; other values may also be helpful, ex., MAP Hz using the MAP/BARO tester). Also refer to Section 7A, Appendix; EEC-IV Graphs and Charts.
- After starting the engine for the road test, enter Engine Running Continuous Monitor Diagnostic Test Mode (refer to Quick Test Appendix, Section 5A).
- Drive the vehicle to create the conditions in which the symptom occurs. If the Customer Information Worksheet from Section 2A has been completed, this information may help in recreating the symptom.
- When the symptom occurs, the passenger should observe changes in listed EEC-IV signals. Information about the symptom, operating condition, value of the EEC-IV signal or other notes should be recorded.
- If the symptom cannot be duplicated, verify that the EEC-IV values are in the expected range.
- Analyzing the Data
- Once the road test is completed, the results should be analyzed to locate and service the fault which caused the symptom (if, for example, a Continuous Memory Diagnostic Trouble Code 639 is set again and the TSS signal stayed within specification, the PCM would be suspect. If the signal went out of specification, the harness or sensor would be suspect).
- If no problem is identified, return to Section 2A for other possible causes of the symptom.