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6 Posts
Discussion Starter #1 (Edited)
Hello All,

I have a Honda CBR 600 F4i which is more or less the same as the earlier version of the RR. The bike will turn over fine but refuses to start and it won't bump start either.

For some background - this problem has happened twice before and on both occasions it simply resolved itself. E.g. when it happened the last time I tried several times to get it to start and failed then two weeks later when I tried again it started first time like there wasn't a problem.

It's now giving me the same problem and I want to find the root cause because it's a lottery whether the bike will start or not.

I have checked the service manual and in the trouble shooting section it states the following where there is no spark:

  • Faulty spark plug
  • Fouled spark plug
  • Faulty ECM
  • Broken or shorted spark plug wire
  • Faulty ignition switch
  • Faulty ignition pulse generator
  • Faulty engine stop switch
  • Loose or disconnected ignition system wires
Nowhere in the list does it state that the Cam Pulse Generator is an issue. However, when I checked the ECM for error codes the only code I am getting is 18 - cam pulse generator. I reset the error codes and tried again and still, just code 18.

In the service manual for code 18 it states:

  • Loose or poor contact on cam pulse generator
  • Open or short circuit in cam pulse generator
  • Faulty cam pulse generator
It states in the symptoms that 'engine does not start'. This is the problem I am having.

I did a circuit check on the wiring harness leading to the connection point to the cam pulse generator and it confirmed there was a circuit. I replaced the cam pulse generator with a known working one. The bike still will not start and it still gives me the same code.

In the trouble shooting section specifically for code 18 it requires a test harness for the ECM and that I crank the engine with the starter motor and measure the cam pulse generator peak voltage at the test harness terminals.

My question at this stage is - with a standard multimeter how do I check the terminals for the cam pulse generator without having (1) a test harness and (2) a peak voltage tester?

If I get 0.7V then this is normal and the result is that I need to replace the ECM.

If I get 'out of range' then I have an open circuit.

I want to believe that I have an open circuit because I have had the problem before and it has fixed itself so I think maybe there is a loose connection somewhere.

Things that I know are working:
The battery is charged;
The spark plugs have been replaced with new ones;
The fuel is fine;
The instrument cluster is lighting up as normal;
The fuel pump is priming.

6 Posts
Discussion Starter #2
I checked the prongs for the connection to the cam pulse generator going back to the ECU and it doesn't register as a circuit (previously I thought it had). I am going to check the wiring diagram and, if it's a straight connection to the ECU, I am going to bypass with a different cable. Hopefully that will work and the problem is that the existing cable is broken somewhere.

6 Posts
Discussion Starter #3 (Edited)
Well today I tried to run a cable direct from the cam pulse generator to the ECU. I ran a cable from the CPG connection point to the ECU where I spliced into the existing wire. The other cable was grounded. Still nothing!

I checked if it was registering as a circuit and it wasn't. Does this mean that the problem is my ECU? It seems that the ECU isn't providing a signal?

I also checked the connection points where the side stand position sensor connects to and this also didn't register as a circuit.

Any advice would be greatly appreciated.
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