505 V6-2849cc 2.8L ZN3J (1987)
Ignition Control Module: Technical Service Bulletins
Ignition - Auto Diagnostic/Detonation LED Flashing
BULLETIN NO. 365 (
1)
DATE:
October, 1989 89
SUBJECT:
IGNITION AUTODIAGNOSTIC/DETONATION LED FLASHING
MODELS:
505 V6 ENGINE VEHICLES
COMPLAINT:
Yellow LED in instrument cluster emits constant flashes
INFORMATION:
The EZ115K ignition ECU incorporates an "auto-diagnostic" feature which enables it to identify eventual malfunctions which could occur during
operation.
These malfunctions are brought to the driver's attention by a yellow LED on the instrument cluster.
The number of flashes (codes) usually identifies the specific component which is malfunctioning.
NOTE:
An occasional blink of the LED indicates detonation sensing and correction, which is totally normal under certain driving conditions,
depending on the quality of fuel being used.
Number of Flashes
Components Involved
Series of 2
NTC Temperature Sensor
Series of 4
Detonation Sensor or Ignition ECU
Series of 5
Erroneous Load Signal from Injection ECU
Series of 6
Number 1 Cylinder Sensor
Constant series of flashes of the LED usually associated with either a fouror six-flash code are in most cases due to intermittent poor electrical contact in
the wiring terminals connecting the components indicated above.
Once the ignition ECU has detected an intermittent electrical problem, the LED will remain in the constant flashing mode until the engine is turned off.
Once the engine is restarted, the ECU will have cleared its memory of the intermittent wiring problem.
The following procedure should be followed prior to attempting to replace any components, which in most cases are not the cause of the problem.
REPAIR PROCEDURE:
I - Locate wiring connectors MC26 and MC27 at cowl panel on right side of brake fluid reservoir:
MC26 is a 9-pin blue connector with wires:
19/19A at pin 1
18/18A at pin 2
- No. 1 Cylinder Position Sensor Wiring
M19A/M21 at pin 3
10 at pin 4
23 at pin 5
- Engine RPM Sensor
M11 at pin 6
M24/M24B at pin 7
24/24B at pin 8
- Right Bank Detonation Sensor
25/25A at pin 9
MC27 is a 4-pin blue connector with wires:
M12/M12C at pin 1
12/12C at pin 2
- Left Bank Detonation Sensor
13/13A at pin 3
M2 at pin 4
- Ground for Ignition ECU/Amplifier Module