TECHNICAL NOTES ON THE EEC-IV MCU - Auto diagnostics

ECM WIRING HARNESS
Eectch98-Part1.fm
The table below lists several MCU cabling pinouts. The first is for a Mustang A9L
EEC, used 1989 to 1993 302 MAF, manual transmission applications. The second, for a
1991 Ranger 2.3L Dual Plug EFI Engine (from Mitchell International On-line manual
(c) 1992), was submitted by . The next three columns
were done by the author and are from the Ford wiring diagrams (yes, I actually
buy the factory manuals) -- and they don't use the same naming convention as the
first two.
No Mustang
A9L
'91
Ranger
2.3
'91 4.9,
5.0, 5.8 Fseries
w/o
E4OD
'91 4.9,
5.0, 5.8 Fseries
w
E4OD
'91 7.3
diesel Fseries
w
E4OD
1 Kapwr Kapwr Bty to load Bty to load Bty to load keep-alive power
2 BOO stop lamp sw to
turn sig sw
stop lamp sw
to stop lamp
Brake On/Off switch
Description
3 VSS + VSS + VSS VSS VSS Vehicle speed sensor positive
4 IDM IDM elect sw to
ignition coil
elect sw to
ignition coil
elect sw to
ignition coil
Ignition Diagnostic monitor
6 VSS - VSS - VSS return VSS return VSS return Vehicle speed sensor negative
7 ECT ECT engine coolant engine coolant xmsn oil temp Engine coolant temp sensor
8 FPM FPM fuel sply pump fuel sply pump
Fuel pump monitor
relay
relay
9 DATA - EEC data - EEC data -
10 ACC ACC compressor compressor
A/C compressor clutch
clutch feed clutch feed
11 AM 2 thermactor thermactor
Air management solenoid 2
diverter valve diverter valve
12 4X4 lo-range 4X4 lo-range
indicator indicator
14 MAF (CA
only)
15 MAF RTN
(CA only)
16 IGN GND IGN GND dedicated GND to
TFI
17 STO/MIL STO/MIL check engine
lamp
(looking at connector from outside MCU)
dedicated GND
to TFI
check engine
lamp
check engine
lamp
Ignition ground
Self-test output check Engine
20 CSE GND CSE GND GND GND GND Case ground
21 ISC/BPA ISC/BPA ISC ISC Idle speed control / bypass air
Table 16: ECM CABLE PINOUT
EEC-IV Technical Notes: Hardware 20 last edited: 9/29/98