Self-Diagnostic System

Fig. 76 ECCS control unit location.:

The self-diagnostic system identifies malfunctions of signal systems such as sensors, actuators and wire harnesses based on the input signals received by the EFI control unit. Various malfunctions are coded and displayed on the control unit by a series of blinking red and green lights. Results of the self-diagnosis are retained in the control unit's memory and are displayed when the mode selector, located on the side of the control unit, Figs. 76, is switched to the On position. When displaying malfunction codes, the code number can be determined by counting the number of light pulses. The red light represents the first digit of the code, while the green light represents the second digit of the code. For example, a Code 32 would be displayed as three flashes of the red light, followed by two flashes of the green light. Malfunction codes can be translated as follows:
a. Code 11 -- Crank angle sensor circuit malfunction.
b. Code 12 -- Air flow meter malfunction.
c. Code 13 -- Cylinder head temperature sensor circuit malfunction.
d. Code 14 -- Vehicle speed sensor circuit malfunction.
e. Code 21 -- Ignition signal malfunction.
f. Code 22 -- Fuel pump circuit malfunction.
g. Code 23 -- Throttle valve switch circuit malfunction.
h. Code 24 -- Transmission switch circuit malfunction.
i. Code 31 -- 1985 Models with A/C, Fast Idle Control Device System malfunction.
j. Code 31 -- 1986 Models. Load signal circuit malfunctioning.
k. Code 32 -- Starter signal malfunction.
l. Code 34 -- Detonation sensor circuit malfunction.
m. Code 41 -- Fuel temperature sensor circuit malfunction.
n. Code 44 -- All monitored systems satisfactory.