Mazda Trucks 1994-1998 Repair Guide

General Information


The distributorless ignition system used by 1995-98 3.0L, 1994-98 2.3L, 2.5L and 4.0L B Series Pick-up and Navajo engines are referred to as the Electronic Distributorless Ignition System (EDIS). It eliminates the conventional distributor by utilizing multiple ignition coils instead. The EDIS consists of the following components:

Crankshaft Position (CKP) sensor
Ignition Control Module (ICM)
Ignition coil(s)
The spark angle portion of the Powertrain Control Module (PCM)
Related wiring

The function of the ICM was incorporated into the PCM beginning with the EEC-V system; otherwise the newer system operates in the same manner.


The CKP sensor is a variable reluctance sensor, mounted near the crankshaft damper and pulley.

The crankshaft damper has a 36 minus 1 tooth wheel (data wheel) mounted on it. When this wheel rotates the magnetic field (reluctance) of the CKP sensor changes in relationship with the passing of the teeth on the data wheel. This change in the magnetic field is called the CKP signal.

The base ignition timing is set at 10 (plus or minus 2 degrees) degrees Before Top Dead Center (BTDC) and is not adjustable.

The CKP signal is sent to the PCM, which uses the signal to determine base ignition timing and rpm calculations.

The one missing tooth on the data wheel creates one large space between two of the teeth. The PCM utilizes this large space as a reference to help determine base ignition timing and engine speed (rpm), and to synchronize the ignition coils for the proper spark timing sequence.

All engines, except the 2.3L engine, utilize one ignition coil pack, which contains three separate ignition coils, whereas the 2.3L engine uses two separate ignition coil packs, each of which contains two ignition coils. Each ignition coil fires two spark plugs simultaneously. One of the two plugs being fired is on the compression stroke (this plug uses most of the voltage) and the other plug is on the exhaust stroke (this plug uses very little of the voltage). Since these two plugs are connected in series, the firing voltage of one plug is negative (with respect to ground) and the other plug is positive.