1988 Dodge Dakota ECM 4379634 3.9L, TBI,
3 speed automatic transmission,
Rear wheel drive
My 88 Dakota died due to a lack of ignition spark. To find the problem I referenced the ignition system troubleshooting section in my Haynes Dakota repair manual. After some testing I discovered that the ignition coil drive transistor in the ECM had shorted and was holding the negative (switched) side of the coil to ground.
The ECM is located on the right fender well behind the coolant reservoir. The computer is cooled thru the engine air intake hose.
I looked around at a couple of salvage yards and didn't find a Dakota computer so I pulled a computer from a 1988 Caravan. The power board was a bit different than the Dakota's so I removed the switching transistor and the suppression capacitor I needed.
1988 Dodge Dakota (SMEC) single module engine controller with the cover removed. Power board with 14 pin connector on top. Logic board with 60 pin connector under power board. The two boards are not electrically connected inside ECM housing.
The ignition coil drive transistor is a Motorola 5206377 and is
mounted on the computer power board.
The ignition drive transistor and suppression capacitor are located on the left side of the board and have been replaced.
The original suppression capacitor was blown apart. It's purpose is to protect the switching transistor from the inductive voltage spikes caused by the ignition coil.
The power transistor is screwed and soldered to the circuit board. I had to simultaneously use a large soldering iron and screwdriver to remove the screws. The soldering iron must be kept in contact with each screw until they are completely removed to avoid ripping up the circuit board traces.
I also replaced the original ignition coil because it didn't have a part number on it and I couldn't verify if it was in spec.