Excessive IOD/Comp Display Error:Transistor Failure (08-26-92)

AJ - ELECTRONIC INSTRUMENT CLUSTER (EIC)

• Intermittent erroneous or erratic display
• Part of display at twice the normal brightness
• Abnormal Ignition Off Draw (IOD) of 40mA or 550mA with no visible indication

AS - ELECTRONIC INSTRUMENT CLUSTER (EIC) (TOWN & COUNTRY ONLY)

• Intermittent erroneous or erratic display
• Part of display at twice the normal brightness
• Abnormal Ignition Off Draw (IOD) of 40mA or 550mA with no visible indication
• Check engine lamp on at all times with ignition on. 40mA IOD
• Check gauge lamp on at all times with ignition on. 40mA IOD

AA, AG, AJ, AN AND AP - MECHANICAL CLUSTER TACHOMETER DRIVE

• Loss of tachometer returning to zero with ignition off
• Abnormal Ignition Off Draw (IOD) of 130mA

AJ & AY - OVERHEAD CONSOLE ELECTRONIC VEHICLE INFORMATION CENTER (EVIC)

• Abnormal Ignition Off Draw (IOD) of 265mA with no visible indications

DETERMINING CAUSE OF DEAD BATTERY - IGNITION ON DRAW (IOD) TEST

The maximum IOD for a vehicle is less than 30mA. The body controller has a thirty second time-out (has current draw for thirty seconds after the ignition is turned off). The Transmission Control Module (TCM) has a 20mA for twenty minutes and the automatic load leveler has up to 500mA draw for sixty minutes after the ignition is turned off or the battery is reconnected. These components must time-out or be disconnected before the IOD measurement is taken.  Follow the IOD procedure.

GENERAL INFORMATION

A normal electrical system will draw from 5 to 30 milliamperes from the battery. This is with the ignition in the OFF position, and all non-ignition controlled circuits in proper working order. The amount of IOD will depend on body model and electrical components. A vehicle that has not been operated for an extended period of approximately 20 days may discharge the battery to an inadequate level. In this case, the Main Fusible Link Connector should be disconnected. The Main Fusible Link connector is located rearward of the battery on the engine wiring harness. See Fig 1 .

Fig 1: IOD Test

If the IOD is over 30 milliamperes, the defect must be found and corrected before condemning the battery. Usually, the battery can be charged and returned to service.

VEHICLES WITHOUT ELECTRONIC AUTOMATIC TRANSMISSION/LOAD LEVELING SUSPENSION OR ALARM SYSTEMS

Testing for HIGHER AMPERAGE IOD must be performed first to prevent damage to most milliamp meters. A standard 12 volt test light and a milliamp meter that is equipped with two leads will be used for the following tests. The milliamp meter should be able to handle up to two amps.

1. Verify that all electrical accessories are OFF. Turn off all lights, close trunk lid, close glove box door, turn off sun visor vanity lights, close all doors and remove ignition key. Allow the Illuminated Entry System if equipped to time out in approximately 30 seconds.
2. Verify the engine compartment lamp bulb is working by opening/ closing hood. Remove the lamp.
3. Disconnect negative battery cable.
4. Connect a typical 12 volt test light between the negative cable clamp and the negative battery post. See Fig 1 . The test light may be brightly lit for up to three minutes or may not be lit at all. This depending on the body model or electronic components on the vehicle.
   1. The term "brightly" used throughout the following text implies the brightness of the test light will be the same as if it were connected across the battery post. This would be with a fully charged battery.
   2. The test light or the milliamp meter MUST be positively connected to the battery post and the battery cable during all IOD testing.
   3. Do not allow the test light or the milliamp meter to become disconnected during any of the IOD teats. If this happens, the electronic timer functions will be started and all IOD tests must be repeated from the beginning. Clamp the test light at both ends to prevent accidental disconnection.
   4. After three minutes time has elapsed, the test light should turn off or be dimly lit depending on the electronics the vehicle is equipped with. If the test light remains brightly lit, do not disconnect the test light. Disconnect each fuse or circuit breaker, beginning with the fuses that feed the M1 and/or M11 circuits, until the test light is either off or dimly lit. Determine what components are on that fuse. Re- connect the fuse and disconnect one component at a time on that fuse and determine if the IOD drops to a normal level under 30mA). Determine which component causes the high IOD and correct the condition. It is now safe to install a milli- amp meter without damage to the meter and check for low amperage IOD.
   5. Possible sources of high IOD are usually vehicle lamp, trunk lamp, glove compartment, luggage compartment, etc..
   6. If test light is still brightly lit after disconnecting each fuse and circuit breaker, disconnect the wiring harness from the alternator. Do not disconnect test light.
   CAUTION: This last test has higher amperage IOD and must be performed before going on with low amperage IOD tests. The higher amperage IOD must be eliminated before hooking up milliamp meter to check for low amperage IOD. If higher amperage IOD has not been eliminated, milliamp meter may be damaged. Most milliamp meters will not handle over one or two amps. Do not hook up meter if test light is glowing brightly. Refer to maximum amperage specifications and instructions supplied with milliamp meter.

   After higher amperage IOD has been corrected, low amperage IOD may be checked. The MAXIMUM IOD = 30 MILLIAMPERES.

5. With test light still connected, connect milliamp meter between battery negative post and negative battery cable. See Fig 2 . Do not open any doors or turn on any electrical accessories with the test light disconnected and the milliamp meter connected. Meter may be damaged.
   CAUTION: Check the components listed in the Symptom/Condition section first. If one of the components is the cause of the excessive IOD, perform the appropriate repair.
   Fig 2: Low Amperage IOD Test

   
6. Disconnect test light. Milliamp meter reading should be less than 30 milliamperes. If low amperage IOD is not within specifications, disconnect the following:
   1. The 60-way connector at the Engine Controller located outboard of the battery.
   2. The 25-way connectors on the Body Controller if equipped.
   3. The circuits to the clock and radio.
   4. The wiring harness from the alternator.

   Check each component until excessive IOD is found. Each time the test light or milliamp meter is disconnected and connected, all electronic timer functions will be activated. Tests must be repeated from the beginning. Test light or meter MUST remain connected for all tests.

VEHICLES EQUIPPED WITH ELECTRONIC AUTOMATIC TRANSMISSION, LOAD LEVELING SUSPENSION, OR ALARM SYSTEM

These vehicles will have temporary high IOD of 15 amps or more for up to 65 minutes. This higher IOD can often mask another problem and should be considered when performing IOD testing. Testing for higher IOD will be the same as in the previous IOD tests. However, certain additional procedures should be followed.

• WITH ALARM SYSTEM: After disconnecting battery and hooking up test light, cycle the key lock on the driver's door to disarm the alarm. The parking lamps should stop flashing. Also locate the Power Distribution Center. This Center is located in front of the left front strut tower See Fig 3 . Remove the cover from the Center and remove the 50 amp fuse.
  Fig 3: Power Distribution Center Location

  
• WITH ELECTRONIC AUTOMATIC TRANSMISSION: If equipped with this option, and high or low IOD is suspected, allow an additional 25 minutes minimum of electronic shut off time. To defeat the timer, disconnect the 60-way connector on the Transmission Controller. This controller is located on the right inner fender.
• WITH AUTOMATIC LOAD LEVELING SYSTEM: If equipped with this option, and high or low IOD is suspected, allow an additional 65 minutes minimum of electronic shut off time.To defeat the timer, open the trunk lid, locate the Automatic Load Leveling computer, located inside right rear wheelhouse, and disconnect the 11-way connector. Close the trunk lid. If equipped with an electrical trunk closing feature, temporarily install a heavy gauge jumper wire between the disconnected negative cable and the negative battery post. When this jumper is installed the trunk lid should automatically close. Do not disconnect the test light as all electronic timing features will be activated and all IOD test must be repeated from the beginning. Remove the temporarily installed jumper wire.

AJ OR AS ELECTRONIC CLUSTER - INTERMITTENT ERRONEOUS OR ERRATIC DISPLAY

This failure may be a constant condition or be extremely infrequent and may reset with cycling of the ignition switch.

1. If the condition is only with one gauge, diagnose and repair as necessary.
2. If the cluster has erratic displays coming across the entire cluster - replace the cluster.
3. If erroneous or erratic display cannot be verified, look for red lines going across the cluster. These red lines would be difficult to see in daylight, but should be easily seen in the dark. Replace the cluster if red lines are present.
4. If customer complains of repeated random or erratic displays (ghosts) appearing across the entire cluster - replace the cluster.

AS ELECTRONIC CLUSTER- CHECK ENGINE LAMP STAYS ON

1. Check engine controller with the DRB II scan tool for diagnostic trouble codes. Repair as required.
2. If no diagnostic trouble codes are found, use the DRB II scan tool to read the status of the check engine lamp. If the engine controller says the lamp is off, but the lamp is on - replace the electronic cluster.

AS ELECTRONIC CLUSTER - CHECK GAUGES LAMP STAYS ON

1. Verify gauges are in the normal operating range. If coolant, volt, or oil pressure gauge is out of range, diagnose and repair the problem as necessary.
   NOTE: No gauge operation with a check gauges lamp on, is an indication of no bus communication. see TSB 08-1492 for more information.
2. Check the body controller for diagnostic trouble codes. Repair as required.
3. If no diagnostic trouble codes are found, but the check gauges lamp is on replace the electronic cluster.
   PARTS REQUIRED
   
   

   Qty.	Description	Part Number
   AR	Tachometer Drive Module - M, AG, AJ, AP and AN	4375410
   AR	EVIC Electronic Board - AY exchange	4685040
   AR	Electronic Cluster - AJ exchange	5269401
   AR	Electronic Cluster - AS exchange	4685011

REPAIR PROCEDURE

This bulletin involves replacement of a defective electronic component as determined by the diagnosis above.

1. Identify the defective component using the Symptom/Condition and Diagnosis procedure above.
2. Select the appropriate replacement part from the parts list above.
3. Replace the component.