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07 Night Train P-0107 Error Code, Need Help!!

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rahmm

New Member
The history, sorry for the long (and first) post.

Bike died just out of the driveway the other day. Backfiring and wanting to stall. Noticed a missing rear exhaust nut. Reinstalled new and tightened.

Cleared the P-0107 (map sensor open/low efi) code and the two P-0131 and P-0151 (02 sensors) codes. The P-0107 code came right back with bike still running badly (wanting to stall and backfiring etc.)

Checked fuses, all good.

Checked battery, it reads 12.78 volts. Good. Disconnected and cleaned ground and reconnected.

Checked all connections and again good.

I assumed it was the map sensor so drove 1 1/2 hrs to pick up new one. After installing it I still have the P-0107.

As per one of Hooples posts I have done the following.

Just took a reading with map sensor plug disconnected and ignition and run switch on, got a reading of 1.28 volts. This was from the black/white (-) to red/white (+). My understanding is this should be 5 volts?

Turned off ignition and unplugged the ECM plug. Checked continuity from violet/white to pin #25, zero.

Next step as I understand it would be to check resistance from green/yellow at map connector to pin #7. In order to do this I need to remove the tank, yet again; as the connector is tough to access.

I thought I'd post first asking if the low voltage on the map plug is a sure sign of a bad ECM or could it be something else? And if so what? I'm stumped and rather than pull the tank unnecessarily I'm looking for any input.

Thanks in advance for any help, this site rocks.
 
rahmm said:
My understanding is this should be 5 volts?
Click to expand...

Your right, it should have read +5 volts.
The +5 reference voltage (pin 14) of the ECM is shared by 3 different sensors. Any one sensor can load or pull down the reference voltage and since error codes have a priority level, the DTC code may not match up to the bad sensor.

The 3 sensors are Map, TPS and Vehicle speed. I would unplug the TPS, VSS and Map sensor and then once again measure the voltage between the Red/White to Black/White wires of any sensor connector. Hopefully you now read +5 volts instead of 1.28 volts. Since the VSS is a hall effect switch, it can easily be internally shorted & loading down the reference.

If you now read +5 volts after unplugging all 3 sensors, your on easy street. I am sure you already figured out what the problem is.
 
Welcome to the forum and kudo's on an outstanding job of searching the self-help section. You started the with a first post that was many posts ahead of the game because of your research first. Great job!
 
Hoople thanks so much for the reply. I'm working night shift and sleep is at a premium. I'll disconnect and check the TPS and VSS in the morning after work.
I'll post the results.
 
Hoople you are the man! It appears that the VSS is the issue as I now have the 5 volts at the Map sensor after disconnecting the VSS. I now have to track one down and hopefully will be back on the move soon.

I don't know where you are but I owe you a beer! Thanks for everything, and I'll say it again. This site rocks!!
 
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