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What is your problem?
VTX 1800 ECM has been trouble free.
Electrical issues are usually the problem.
 

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Discussion Starter #3
Rear cylinder had no spark
I checked the coil and it is okay as I swapped them. The is no trigger supply from theecm and I opened the wiring harness from theecm and find that the wire is burned as it has grounded on the frame. The yellow/silver dot wire that is attached to the yellow/greenfor the rear coil. This wire runs the techo on the 2004 but 2002-3 has no wire connection to the techo. The ecm itself has swollen as well.
 

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Rear cylinder had no spark
I checked the coil and it is okay as I swapped them. The is no trigger supply from theecm and I opened the wiring harness from theecm and find that the wire is burned as it has grounded on the frame. The yellow/silver dot wire that is attached to the yellow/greenfor the rear coil. This wire runs the techo on the 2004 but 2002-3 has no wire connection to the techo. The ecm itself has swollen as well.
The hard ground should not have affected the driver transistor IMO. It should put out a Ground to trigger the Ign coil, and go open when in the Off state.

Do you have good +12v at the Black/White wire. It would have the same current flow as the grounded trigger wire.
 

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Which sensor supply the ecm to generate this ground voltage.
Crankshaft Position Sensor(CKP) and Camshaft Position Sensor(CMP) are part of the Ignition Pulse timing.
Since the front spark plug has fire they are good.

On the ECM schematic the the Ign coil driver wires (Bu/Y, Y/Bu) are shown next to a G/P(Green/Pink) Ground wire which is directly connected to the
Common Electronics Ground bolt at the Front Ignition coil. CHECK all IGN coil wiring. Put a lamp/bulb on the rear Ign coil wires and verify you can turn it on with a Ground at the ECM connector.

Check the Bl/W wire at the rear coil for +12 volts. When the coil driver transistor is OFF, the +12v is on the Bu/Y and Y/Bu pins to the ECM.
When the coil driver transistor is ON, the Bu/Y and Y/Bu wires provide a Ground to the coil. Coil builds a magnetic field, when driver transistor is turned OFF,
the collapsing magnetic creates high voltage in the coils.

Section 17 of Service Manual is the Ignition section.
Honda has a spec of 100v peak voltage minimum on the coil, this would be the Bu/y or Y/Bu depending on which coil is be tested.
The peak voltage adapter is a diode and a capacitor.
 

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Discussion Starter #7
Hans & feet
Thank you for your undivided response and helpful info. I'll update you as soon as I get to the cruiser.
 

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Discussion Starter #8
Hans&feet
I've conducted the test for the coils to see if they are working buy supplying ground power to the trigger wire and indeed they are ok. While the bike is idling and i wiggled the ground on the trigger wire, the idling change a little for that one cycle rotation because i matched that timing. So i believe my ecu trigger supply is dead.
Do the ckp wires Y and W/Y supply their signal individually?
Can a 38770-MCV-671 CDI BOX work at 38770-MCH-672 CDI BOX based on the wire schematics?
 

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Both wires are involved in the output of the CKP sensor. It generates a signal.

Look at the Camshaft Position Sensor connector. (CMP) at Left front cylinder.
One 1800 owner just had a bad connection on his.
https://www.vtxoa.com/forums/6-vtx-1800-tech-board/463032-no-spark.html

This Honda 38770-MCV-671 PGM-FI UNIT fits the following models and components:
Honda Motorcycle 2002 VTX1800R A Wire Harness
Honda Motorcycle 2002 VTX1800S A Wire Harness
Honda Motorcycle 2003 VTX1800R A Wire Harness
Honda Motorcycle 2003 VTX1800S A Wire Harness
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This Honda 38770-MCH-672 PGM-FI UNIT fits the following models and components:
Honda Motorcycle 2002 VTX1800C A Wire Harness
Honda Motorcycle 2003 VTX1800C A Wire Harness
Honda Motorcycle 2004 VTX1800C A Wire Harness

I do not see anything different other than R/S Calif model has 2 - O2 sensors; C Calif has 1 - O2 sensor

Are the wires on different pins???? Doubtful.
Different programming for 2 into 1 exhaust?? Possible.

1800 owners that have done ECM changes may know that.
 

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Discussion Starter #10
Are the wires on different pins???? Doubtful.(they are on the pins)
Different programming for 2 into 1 exhaust?? Possible.(i believe so)
I may be wrong that but if i get a 671 ecu i think it can function the same as 672 ecu.

Ok. Today i measured the voltage output wwith a multimeter from the ECU on both trigger wires to the coils.

Is this normal to measure a (+power)Y/BU(trigger wire) on the front firing cylinder and (-power)BU/Y(trigger wire) on the rear non-firing cylinder while the engine is running?
 

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In the non cranking state with Ignition On and kill switch in Run position plus +12v should be on both Bu/y and Y/Bu..
In the cranking state ECM puts out Ground pulses, but
The collapsing magnetic produces a high voltage positive pulse. That is why Honda uses a peak adapter...

A diode and a capacitor make up the peak adapter that is used with a DMM...
My VTX at idle 174 volts peak DC voltage, at higher RPMs up to 276 peak volts DC
Honda wants 100v minimum peak voltage at cranking I believe.
 

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I received a PM today from Mcgyevor.
Thanks for the info you shared with me regarding my ecu issue. I finally orders an ecu from USA of 2002 vtx 1800C ******671 though mine is ******672 and my bike is now running smooth firing on both cylinders.

Whatever the difference between ECM for R/S vs C is, it worked. 1st Gen 1800.
 
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