Re: audible alarm engine cranks wont start
MEFI-3 and Audio Warning
The MEFI-3 engine’s Audio Warning system will sound the alarm differently and it has more
items that will cause it to sound.
There is what is called a ‘soft’ and a ‘hard’ alarm.
1. Soft Alarm = Below 3000 rpm. Horn on for 1 second, off for 3 seconds, on for 1 second,
off for 3 seconds, etc.
2. Hard Alarm = Above 3000 rpm. Horn sounds all the time.
Audio alarm sounds for the same malfunctions as MEFI-1 and -2;
1. MCM - Low lube level in Gear Lube Bottle. [General 1] or MIE - High Transmission fluid
temperature [General 2].
2. MCM/MIE - Low engine oil pressure.
3. MCM/MIE - Too high engine coolant temperature.
Early production and service ECMs had the following items that will sound the
alarm;
1. MCM/MIE – Horn will sound if there is an active engine Diagnostic Trouble Code [DTC]
that is occurring while the engine is running. The horn will not sound a stored DTC.
Correcting the DTC malfunction will stop the horn.
2. MCM/MIE – Horn will sound if the battery voltage to the ECM is low, [less than 9v for at
least 5 seconds]. Using the throttle lever to increase engine rpm to get the alternator to
put out more voltage will correct most low voltage problems.
3. MCM/MIE – V6 and V8 305/350 cid engines only. Horn will sound if there is low fuel
pressure [for at least 5 seconds]. These engines have a fuel pressure sensor. The EFI
engines have the sensor in the throttle body unit and the MPI engines have the sensor
located in the port fuel rail toward the rear of the engine. Correcting the cause of the low
fuel pressure will stop the horn.
The ECM checksums listed below have these additional alarms turned ON in them.
NOTE: Later production and service replacement ECMs have these extra alarms
turned off. If the ECM checksum is different from the ones listed below, the extra
alarms in that ECM is turned OFF.
MCM 4.3L EFI: ECM never had these extra alarms turned on.
MCM 5.0L EFI: With D04B or D074 checksum.
MCM 5.7L EFI: With D7ED or D798 checksum.
MCM 350 MPI, MCM 350 MPI Horizon, MIE 350 MPI Ski, MIE 350 MPI Inboard or MIE 350
MPI Horizon Inboard: With E60D or EAED checksum.
MIE Black Scorpion: With BB98 or BB42 checksum.
MCM 7.4L MPI or MIE 7.4L MPI Inboard: With FE28.checksum.
MCM 454 MPI, MCM 454 MPI Horizon or MIE 454 MPI Horizon Inboard: With EBC4 checksum
You have probalby disconected a sensor it is all... Ok lower back midde side of the engine ... Knock sensor... look at that wire connector type and inspect all wirng going from the pump area up to the ecm..temp sensor there map sensor etc
