B18C ICM Failing? - Bad Ignition - D Series ICM into the B Series (OBD 1)

/DIY-Ignition-Control-Module-(ICM)-Replacement.-Lots-of-Pics

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Brand: Tridon
Part: Ignition Control Module
Part No: TIM032
Application: B18B2
Origin: Australia
Warranty: Lifetime (The OEM part is made by NEC and OKI which only lasted 15 years =P)





I used some spare D series ICM and Coil into my B series.
Note that the heatsink of the ICM is different, It bolts to the dizzy different. I forced the ICM onto the B series heatsink

And the reason for smashing the old ICM was that I didn't know it was bolted on the underside (totally diff from the D series)





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/17-audio-security-electrical/163657-anatomy-b-series-distributor.html

Now on to the more important part of the distributor: the ignition.

The most important part of the system is the coil. It is an induction coil- being that it creates a high voltage from a lower voltage. Here's some further reading. So what happens is the primary coil windings have 12V applied to them. Wound inside of the primary winding is the secondary coil. There is a much larger number of windings- so as to produce the higher voltage. When the 12V is removed from the primary coil, the magnetic field that was formed suddenly collapses, which sends a very high voltage pulse through the secondary coil...and thus we have a spark.

Let's take apart the distributor and take a look. First take the cap off (3 screws) then the rotor (1 screw- it can be a pain!) Next pull out the dust cover. There are 2 wires on the coil (I'll get to that in a minute)- just unscrew them. Be careful not to strip them! They are likely a bit worn from age. Next, remove the 2 larger screws on the top of the coil shown here:

Next is the ICM or ignition control module (also called the Ignitor). Think of it like a VERY expensive relay. What it does is control the amount of time that the coil is charged with +12V (this is known as ignition dwell) as well as remove that voltage thus creating the spark. The ICM is also responsible for creating the tachometer signal. This is why it is a very good sign when the tachometer is acting up, it is time to replace the ICM.

The ICM has 4 wires connected to it. They are: +12V, coil control wire, tachometer output, and input from the ECU. The ICM is grounded externally through the body.

Now that our cars are getting older, I am seeing more and more ICMs that are going dead. Some symptoms are:
-Random tachometer jumping
-A completely unresponsive tachometer
-The engine suddenly shutting off while driving- you will be rolling and still in gear...but the tach may or not be responding, and you will have little or no power.

The OEM Honda ignition system is sensitive. While I have seen several ignition modifiers (MSD, Crane, etc) and external coils used with success, I have seen WAY more that cause problems. I have personally seen an external MSD coil kill 2 ICMs on my old car. It has been proven over and over that the OEM ignition system will hold up to VERY large amounts of power. I am in no way saying that these aftermarket products are bad in any way, I am simply saying that the Honda ICM was made to work with the Honda coil, and they work very well in harmony. Don't go buy a hot new igntion box or coil...just replace the parts of your OEM system.

*see above the heat sink differences. B vs D series.
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Coil and ICM Input Test - /Coil-and-ICM-Input-Test

DIY Coil and ICM Input Test
Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk.

I have notice a few threads with people with no start/cutting out problems, so i thought i would make a DIY article to try help out. NOTE these specs are an average as most models have different specs so if you readings are close they are probably correct.

Undo the 3 bolts and remove the distributor cap. Remove the rotor button, it may have a screw in it if so remove it if not use a screwdriver to gently pry it off. Then remove the leak cover.

IGNITION CONTROL MODULE INPUT TEST

1. Remove the wires from the ICM

2. Turn the ignition switch to ON. Check that there is battery voltage at the wire that came off terminal C and body ground

3. With the ignition still on check there is battery at the wire that came off terminal B and body ground. If there is no voltage test your coil.

4. Check for continuity between the wire that came off terminal D and the ECU

5. Check for continuity between the wire that came off terminal A and the Tacho

6. If all test are normal replace the ICM

TESTING A COIL

1. Grab your multimeter and put it on the Ohms setting. Measure the Primary Windings resistance between the A and the B terminals, it should be about 0.7 Ohms.

2. Now change your settings to Kohms and measure the Secondary Windings resistance between the A and secondary winding terminal C, it should be about 17 Kohms.

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Gear I found as possible replacements for the OEM igniter and ICM.

MSD Megarace coil
MSD 6A digital ignition (A mallory Hyfire 6 Digital ignition can do as well for those that don't like MSD)
MSD external cap
NGK 8.5 wires

MSD 8207 Coil instead of the Crane coil.

The summitt and mallory boxes even have an ignition rpm limit adjustment to work as a safety measure.

summit box and crane coil - summit box and crane coil. And they can be used with the icm bypass

MSD 8207 Coil instead of the Crane coil. The summitt and mallory boxes even have an ignition rpm limit adjustment to work as a safety measure.

The icm is a failing point due to being mounted inside the distributor and heat and load. You can run the msd off the positive coil trigger from the icm but they eventually fail. The bypass circuit allows signal from ecu to the msd or box of your choice without the ignitor and gets rid of that failing part with just a circuit

Mallory Hyfire and MSD 6A digital boxes

Summit Racing Digital Capacitive Discharge Ignition Box
MSD Distributor Rotor
MSD Pro Distributor Cap
Mallory External Coil

Summit racing street ignition box, Mallory racing coil, ignitor bypass (turbo-LS) & MSD distributor cap

M&W Pro 10, Crane Cams LX92 Coil, and MSD Cap external Coil Cap