How to Check the First Generation DSM ECU for an EPROM
does not assume any responsibility for the use of this document or its
Here is a handy table which you can print out to record your ECU
information. As long as you have your ECU open, you might as well record this
information so you will have it available if you order an ECU upgrade.
||1.8l / 2.0l / turbo|
||CA or similar / Federal|
||Auto / Manual|
||YES / NO|
|ECU part number
||YES / NO|
|Microcontroller Code #
||YES / NO|
||YES / NO|
- Locate the ECU. Figure 1 shows
the ECU in the center console, underneath the radio. To get to the Figure
2 views below, you will have to remove the center console carpeted kick
panels from both the driver and passenger sides.
- Unplug the ECU. Figure 2 is a
view of the ECU if you could see the front of it using x-ray vision from the
front bumper. Note that the connectors have release-tabs pointed towards the
front of the car. It is a bit difficult to figure out how to get the plugs
pulled at first, so go slowly and wiggle the plugs out carefully. You might
find it easier to skip to the next step and remove the plugs after the ECU bolts
have been removed.
- Unbolt the ECU.Figure 3a is a
picture from the driver side and Figure 3b is a picture from
the passenger side (your views might be slightly different depending upon stereo
equipment options installed). The passenger side picture shows a lot of wires
that were added for a rallye computer that most likely won't be in your car.
the ECU out
- Remove the ECU. First, shake the ECU a bit to get
it off the notch tabs. Then, slide the ECU out as show in Figure 4.
There are three bolts that hold the ECU in place (circled in yellow). When
removing the ECU, you might have to wiggle it around a bit - there are other
wiring harnesses in the area, making for a tight squeeze.
- Open up the ECU. There are four screws on the
outside of the case.
Be absolutely certain that you are using the correct size
Phillips screwdriver. For some reason, they put tons of torque on some of the
ECUs screws. The wrong size head will lead to stripping the screw heads.
ECU with an EPROM
ECU without an EPROM
- Check for the EPROM. Figure 5a
shows an ECU with an EPROM which has been circled in red. Figure 5b
shows an ECU with no EPROM and has a blue circle indicating where the EPROM
should be. If you have no EPROM, any ECU upgrade will involve the use of a
daughterboard which plugs into where the microcontroller chip is (green circle).
- Gather part numbers. The EPROM in Figure
5a has an EPROM number of EB21 (circled in red). The microcontroller
number is circled in green. We are interested in the number of the form EXXX.
On this particular ECU, the number is E853. Ignore the numbers "MH6111"
and "76C75T" - these are internal Mitsubishi part numbers only. In
the middle of Figure 5a, there is a board revision number
(circled in blue). This ECU has a rev number of JE331B989A. There is also an
ECU part number stamped on the ECU harness connector (circled in purple). This
ECU has part number 0879E.
- Check the ConfigID. There are two
configuration-identification resistors. The existence or absence of these
resistors let the ECU know things about the engine it will be controlling. In
this way, Mitsubishi can build one ECU, solder one of four different resistor
combinations in, and re-use that ECU for four different engine packages. These
resistors are R129 and R130 (circled in yellow in Figure 5a).
Please note whether or not there are resistors soldered in at those two
- You are done! Reverse the above steps to
re-install your ECU. Remember that it is much easier to first plug the ECU in
before installing the ECU bolts. You also might want to have a friend help you
put the ECU back up on the tab holders.