|86-89 2.8L VIN S MFI
||Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds
during closed loop operation after the engine had been running for 2
minutes and the throttle angle was above 4%.
||Coolant temperature sensor signal indicates a temperature of over
275° F for 3 seconds.
||Coolant temperature sensor signal indicates a temperature colder than
-47° F for 3 seconds.
||TPS voltage was above 2.5 volts for 5 seconds when the MAP sensor
signal showed manifold vacuum above 15 pounds or TPS signal voltage
was over 4.5 volts.
||TPS voltage was under 0.2 volts for 3 seconds when the engine was
||Manifold air temperature sensor signal showed an air temperature of
-31° F for 3 seconds after the engine has been running for 8 minutes.
||When engine speed was between 1400 and 3600 RPM and throttle angle
was less than 2%, the MAP sensor signal showed low voltage (High manifold
vacuum) for at least 3 seconds.
||Manifold air temperature sensor signal showed an air temperature over
293° F for more than 3 seconds after the engine has been running for
4 minutes and a vehicle speed was present.
||EGR vacuum switch was closed during start-up or idle, or EGR vacuum
switch did not close when EGR solenoid was commanded to close by ECM
for 5 seconds.
||MAF sensor indicated air flow was more than 20 gm/sec for 2 seconds.
||MAF sensor signal showed air flow to be less than 2 gm/sec or the
MAF circuit was shorted.
||The number of crank reference pulses did not match the number according
to the PROM when engine speed was under 2000 RPM, or the incorrect PROM
has been installed.
||The EST signal did not change when the ECM applied bypass voltage
to the ignition module.
||Oxygen sensor voltage was under 0.2 volts for 60 seconds of closed
||Oxygen sensor voltage was over 0.7 volts for 30 seconds in a closed
loop when throttle angle was between 3% and 45% and engine had been
running for at least 1 minute.
||Charging system voltage was greater than 17.1 volts for 2 seconds.
Repair charging system.
||Fuel pump signal voltage was less than 2 volts for 1.5 seconds.
||ECM error. Replace ECM.