Toronado V6-231 3.8L (1986)
Technical Service Bulletin # 92T141A
Date: 930201
BCM - Codes E047, B333,B334,B335,B336/B337-New Diagnosis
NUMBER: 92-T-141A
CORP.REF.NO: 018112R
DATE: February 1993
SECTION: 6E3, 8A, 8D2
SUBJECT:
CODES E047, B333, B334, B335, B336, AND/OR B337 - NEW DIAGNOSIS PROCEDURE
MODEL/YEARS:
1986-92 TORONADO/TROFEO
This bulletin cancels and supersedes Dealer Technical Bulletins 90-T-195 and 92-T-141 which should be discarded.
Some 1986-92 Toronado/Trofeo models, may exhibit intermittent setting of data line codes E047, B333, B334, B335, B336, and/or B337. These may all
be set at one time or in any combination. Single codes should be diagnosed using the appropriate trouble tree in the Toronado/Trofeo Service Manual. In
addition to the codes, some of the following may also occur:
^
IPC, CRT, and/or the HVAC/ECC flashes on and off or bright/dim
^
Trip odometer resets to zero (0)
^
ECC switches to full heat at high blower speed out the front defrost ducts
^
Erroneous displays appear on the IPC or ECC
^
ECC panel will not respond to pressing of buttons
^
CRT, DIC, or ECC may display SYSTEM PROBLEM
These conditions may be caused by either a damaged data line circuit or one of the components connected to the data line. When operating normally, the
serial data line voltage should continually fluctuate from 0 to 5 volts.
DIAGNOSIS:
If the serial data line has been shorted to ground, the voltage at the Assembly Line Data Link (ALDL) will be 0 V. If it has been shorted to voltage, it will
be over 5 V. If one of the components on the serial data line is affecting the data line voltage, the serial data voltage at the ALDL connector will be a
steady value anywhere between .1 and 5 volts (e.g., 2.7V, 4.8V, etc.).
Description of Data Line Conditions
This section explains how to find the cause of a data line condition that is present all the time or can be duplicated for diagnosis. Using the instructions in
this section, perform the appropriate "condition present diagnosis" trouble tree.
The condition present diagnosis charts have many branches that instruct to check for voltage/ground on the 800 circuit. First, check for voltage at the
specified pin with the ignition on (there should be less than .1 volts). If there is no voltage, check the circuit for resistance to ground (should read open to
ground on the highest resistance setting). The trouble trees are written so that whenever these checks are made the right components are
connected/disconnected to prevent false readings. Therefore, do not reconnect components until instructed to do so or when diagnosis is completed.
If the voltage/resistance test indicates there is a problem in part of the 800 circuit, check that section of the 800 circuit by tracing the wire and checking
connections in that segment. Refer to page 8A-50-0 in the Chassis Service Manual for circuit layout. If the circuit is difficult to trace or no problem in the
circuit is visible, it may be better to restring the segment involved.
Note:
Data line conditions tend to be intermittent and may disappear while disconnecting/reconnecting components. Therefore, double check each step of the
trouble tree to make sure the conditions have not disappeared during testing. If they have disappeared, return to the last step taken while the condition
was present and continue when condition returns. If the condition cannot be duplicated again or the condition present diagnosis does not lead to the fix,
perform the condition not present diagnosis.
CONDITION NOT PRESENT:
Sometimes the conditions can be duplicated by carefully warming the data line components with a heat gun and/or lightly tapping on them. If the
condition cannot be duplicated on the vehicle during diagnosis, follow the procedure below:
1.
Make sure that the grounds on the block near the starter solenoid or behind the power steering pump behind the engine block and on the fender
near the battery, are clean and tight. Make certain there are star washers on the stud and that the studs are free of corrosion.
2.
Check the BCM EPROM and EEPROM and ECM PROM or MEM-CAL assembly for proper insertion into their respective sockets. Inspect
