P1608

P1608 ECM - ETS Communication Line-Malfunction (EMS -> ETS)

General Information





Component Location

General Description
There is a communication line between PCM and ETS unit.Using this communication line ,various data,such as throttle target angle,TPS output,APS output and diagnostic trouble codes regarding ETS motor,TPS and APS are communicated between PCM and ETS unit. A malfunction is detected by using a checksum technique for verifying data. The digital data is composed of zeros and ones. A checksum is the total of all ones in a string of data. By comparing the checksum value with a stored value, a malfunction can be detected.

DTC Description
If the communication between PCM and ETS unit is abnormal, this DTC is set.





DTC Detecting Condition





Schematic Diagram





Connector View

Terminal & Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?

YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.

NO: Go to "Communication Circuit Inspection" procedure.

Communication Circuit Inspection
1. Check for open in harness
(1) Ignition "OFF"
(2) Disconnect ETS unit connector and PCM connector.
(3) Measure resistance between terminal "8" of ETS unit harness connector and "11" of PCM harness connector.
A. Specification: Approx.below 1 ohm





(4) Is the resistance within specifications?

YES

- Substitute with a known-good ETS unit or PCM and check for proper operation. If the problem is corrected,replace ETS unit or PCM and then go to "Verification of Vehicle Repair" procedure. If ETS unit needs to be replaced, do initialization after it is replaced.

NO

- Check for open in communication harness, Repair as necessary and then go to "Verification of vehicle Repair" procedure.

Note:
- Procedure of ETS Initialization
1. Erase the trouble codes on PCM
2. Turn the ignition key on less than 1 second and turn it off(Do not start the engine)
3. Turn the ignition key off and keep this condition until the main relay is turned off.(It will takes 10 seconds)
4. Turn ignition key on more than 1 second to record the throttle motor position on the EEPROM

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness test have been verified as " Complete "
5. Are any DTCs present ?

YES: Go to the applicable troubleshooting procedure.

NO: System is performing to specification at this time.