Accel/dfi – Mallory Ignition ACCEL CHEVROLET APPLICATIONS (including LT-1) 74022 User Manual

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ACCEL/DFI

any of these harnesses please contact your dealer immediately.
Make sure to connect the switched +12 volt wire (long pink
wire with a female spade connector) to a switched ignition
accessory in the fuse box. The switched ignition accessory
must maintain 12 volts during cranking, if it does not the
vehicle will not start.

NOTE:

If you are not controlling timing with the

ACCEL/DFI ECM (using a non-computer
controlled HEI, points distributor, etc.) you
will not be using the computer controlled HEI
connector (4-pin male black connector) or the
ESC connector (1-pin female black connector).

The passenger side harness leg will contain the following

sensor connections:

• Oxygen (3-pin female black connector)

• Injector (5-pin round white connector)

• Tach pick-up (1-pin brown connector)

• Fuel pump (bare lead, red wire with

white stripe)

• IAC (4-pin square male black connector)

Connect each to the appropriate sensor using Figure B as a
reference. If you need to lengthen the fuel pump wire to
reach your fuel pump, make sure to use at least 14 gauge
wire. Finally, be sure to connect both the positive and ground
terminals of the MWH DIRECTLY to the battery. If you fail to
do this intermittent and unusual problems may occur.

NOTE:

If you are controlling timing with the

ACCEL/DFI ECM (using a computer controlled
HEI, TFI, etc.) the Tach pick-up will not be

used. If you connect the Tach pick-up and the
Computer controlled HEI connector at the same
time, your ECM will cancel both of them out,
resulting in a no spark situation. In many cases
this will also damage your ECM.

At this time you can connect your User Interface Module
(UIM, or Power Tuner) to the MWH by connecting the 6-way
connector (located near the ECM connectors) to the 6-way
connector on the UIM. If you did not order a UIM there is
nothing for you to do with the 6-way connector on the main
harness. If using a UIM, mount the unit with two (2)
#8 sheet metal screws or pan head screws with nuts,
in a location convenient to the driver. See section XII for
description.

NON-COMPUTER CONTROLLED IGNITION

If you are using a non-computer controlled HEI (prior to
1985), points style distributor, etc. the Tach pick-up (1-pin
brown connector) must be used. Connect this lead to the
negative side of your coil. If the brown connector must be
removed for your application, be sure not to remove the 39K
ohm resistor which is 3” from the existing connector.

NOTE:

If you are using an aftermarket ignition

enhancer box (i.e.: ACCEL 300+, MALLORY
Hyfire) the MWH’s Tach pick-up connector
MUST be connected to the enhancer box’s Tach
output signal. It is also necessary to remove the
39K ohm resistor from the Tach pick-up wire. It is
3” from the end of the Tach pick-up lead. DO
NOT connect this lead to the negative side of
your coil if using an enhancer box, this can result
in ECM damage.

VI – CHOOSING YOUR DISTRIBUTOR