Ignition - Poor Driveability, No Start/Code E12,23,28,30
88cadillac13Bulletin No. T-89-36
File in Group 6E
Number 66
Corp. Ref. No. 816529
Date Nov. 1988
SUBJECT: ROUGH IDLE, INTERMITTENT NO START, CODE E12, E23, E28, OR E30, DETONATION AND/OR ERRATIC IGNITION SECONDARY SCOPE PATTERNS
MODELS AFFECTED: 1988 DE VILLES, FLEETWOODS, ELDORADOS, AND SEVILLES
Some 1988 DeVilles, Fleetwoods, Eldorados, or Sevilles may experience one or more of the following symptoms:
^ Rough idle, may be intermittent when cold, hot, or under high electrical loads (i.e., A/C compressor, rear window defogger on).
^ Erratic ignition secondary scope patterns (i.e., double firing lines).
^ Detonation (spark knock) at idle or acceleration.
^ Intermittent no start or no crank.
^ ECM trouble code E12, E23, E28, or E30.
Any of the above conditions may be caused by high resistance in the vehicle ground circuits, which can disturb the ECM ground, circuit 450. High resistance may be due to a loose or corroded connection, or an open or frayed circuit in the battery negative cable.
If the condition is intermittent, checking the resistance of the ground circuit may not be an effective diagnostic test to confirm a ground problem.
Therefore, to diagnose this condition:
1. Install a jumper wire from the generator frame to the negative post of the battery.
^ If the condition is still present, refer to the appropriate section of the 1988 Cadillac Service Information Manual for diagnosis.
^ If the condition is eliminated, remove the jumper and go to step 2.
2. Check for loose or corroded ECM or engine ground connections.
NOTE: All ground connections must be CLEAN as well as tight. Disassembly of the ground is required to accurately check for corrosion and/or painted surfaces. If corrosion or paint is present on either mating surface, it should be cleaned with a wire brush before being reinstalled. A starwasher should also be installed for all metal to metal electrical joints.
1988 Service Information Manual page numbers have been included to show the ground locations.
^ DeVille/Fleetwood
G100: Engine compartment ahead of left hand wheelhouse . . . . . . . . . . Page 8A-201-3,
Figure A
G101: Right hand side of engine on generator mounting bolt . . . . . . . . Page 8A-201-0,
Figure A
G105: Right hand side of engine compartment on fender stud . . . . . . . Page 8A-201-5,
Figure A
G110: Right hand side of engine below rear valve cover . . . . . . . . . . . . Page 8A-201-0,
Figure B
NOTE: The proper installation sequence is: the power steering bracket, O2 sensor/ECM ground eyelet, starwasher, and nut.
Negative Battery Cable - on stud near starter motor.
^ Eldorado/Seville
G100: Right hand front of engine compartment in front of battery . . . Page 8A-201A-2,
Figure A, hem 17
G101: Top right hand side of engine on generator bracket,
not shown in manual
G102: Right hand end of rear cylinder head . . . . . . . . . . . . . . . . . . . . . . Page 8A-201-0
Figure A
G103: Lower front of engine right of starter solenoid . . . . . . . . . . . . . . . Page 8A-201-1
Figure C
ISO Ground Junction Block: Right hand side of engine compartment . . . Page 8A-201-3 Figure A
3. If the condition is still present and the appropriate ground connections are clean and tight, replace the battery negative cable.
For warranty purposes use Labor Operation N0126 at .2 hour for DeVilles and Fleetwoods and .7 hour for Eldorados and Sevilles.