Enhancement Program - Service Action Procedure: Overview
04-12Enhancement Program - Service Action - Procedure
MODEL: 93 MY 4.0L Sedans
DATE: 11/93
Issue:
The workshop procedures described in this enhancement package resolve the following potential service problems:
Premature Bulb Failure
Premature bulb failure is caused by excessive voltage at the bulbs. Production vehicles now have voltage dropping diodes fitted at each bulb failure module and a resistance link lead in each harness for the headlights. Long life bulbs are now fitted in the tail lights.
Bulb failure modifications introduced: VIN 685497
Radio Re-coding/Poor AM Reception
The radio intermittently requiring re-coding and/or having poor AM reception is caused by the retaining nut at the antenna coax cable connection being loose, giving a poor radio chassis ground.
Antenna coax cable nut tightness assured from VIN 685497
Water Ingress Into The EMS ECM And Lower "A" Post Connectors
The cause of water ingress is poor drainage of the plenum chamber. On production vehicles this has been resolved by installing an extended drain tube. Damage to electrical components due to water ingress has also been avoided by introducing a shroud for the EMS ECM, foam seals for the lower "A" post connectors and applying water-proof grease to the connectors.
Extended plenum drain tube introduced: VIN 681967
EMS ECU and lower 'A" post sealing introduced: VIN 683199
A/C Trinary Switch Failure
Failure of the Trinary Switch is caused by mechanical vibration being applied to the Trinary switch by the Slow Fan Pressure Switch when it operates. The vibration oscillates the contacts of the Trinary Switch causing arcing and deposition on the contacts and eventually, an open circuit condition. The Slow Fan Pressure Switch is now mounted on a rubber extension hose to eliminate the vibration.
A/C Slow Fan Pressure Switch relocation introduced: VIN 687220
Erratic Engine Load Signal - Secure Air Mass Meter
Erratic engine load signal can be caused by the degradation of the mass air flow sensor connection.
Intermittent Flagging of FF 12
Engine management diagnostic trouble code (DTC) 12 can be flagged if the ignition is switched off when the engine speed is above 1500 RPM.
A capacitor within the EMS ECM maintains power to the ECM momentarily after the ignition has been switched off. The crank sensor still detects that the engine is running but the air mass flow meter is off. The OBD system assumes that a fault exists with the air mass flow meter and reads FF 12.
A link harness and revised main fuel injection relay have been introduced to rapidly discharge the capacitor when the ignition is switched off.
Link harness and new fuel injection relay introduced: VIN 677925
Momentary Illumination of Instrument Pack
This can occur when the front wheels pass over large metal objects, i.e. a manhole cover or R/R tracks, due to discharge of static electricity build-up. The front hubs are now grounded to the chassis of the vehicle.
Front hub ground straps introduced: VIN 685240
Warranty Information