P1108 code

[Hammer]

Hey Guys,

'05 classic. I have a p1108 code that wont clear, just keeps coming back. Ambient air pressure sensor circuit high voltage. Service manual says to unplug the sensor and check for short between ecu pin A01 & A23.

So first off, im confused as to which sensor is the ambient air pressure sensor. The manual lists the following;

Air Pressure Sensor
MAP Sensor
Inlet Air Temperature Sensor

And then descirbes the following;

Intake air temperature sensor - situated at
the front of the intake duct, above the camshaft
cover. As the density of the air changes with
temperature (therefore the amount of oxygen
available to ignite the fuel), an intake air
temperature sensor is fitted. Changes in air
temperature are compensated for by adjusting
the amount of fuel injected to a level consistent
with clean combustion and low emissions.

Barometric pressure sensor - situated
beneath the motorcycle seat, in the top of the
airbox. The barometric pressure sensor
measures atmospheric air pressure. With this
information, the amount of fuel per injection is
adjusted to suit the prevailing conditions.

Manifold Absolute Pressure <MAP) sensor
- situated at the front of the intake duct, above
the camshaft cover, connected to each of the
three throttle bodies by equal length tubes. The
MAP sensor provides information to the ECM
which is used at shallow throttle angles (very
small throttle openings) to provide accurate
engine load indications to the ECM. This
degree of engine load accuracy allows the ECM
to make very small adjustments to fuel and
ignition which would otherwise not be possible
from throttle angle data alone.

Based on that I've assumed that Air pressure sensor = Intake air pressure sensor = Ambient air pressure sensor. Correct me if I'm wrong.

I then unplugged it and did the continuity test between ecu pin A01 and A23. No continuity which leads to a wire issue. I happen to have a spare wiring harness, so I grabbed it and it as well does not have continuity between those pins. Having a hard time believing both harnesses have the same wire issue.

Also is the Air pressure sensor/Intake air pressure sensor/Ambient air pressure sensor supposed to be hooked up to a vacuum line? I currently have it hooked up to a line that goes to the 4 way T fitting, connected to the 3 lines that go to each throttle body. I'm assuming this is proper but I've had this bike apart so many times its hard to remember.

I do have a rammair fitted.

Thanks in advance guys.

 

[warp9.9]

Ok bud im not a electrical guru but lets see what or if I can help. I even got the book out. And lets talk about your last paragraph. Sonce your wanting to check the ambient pressure sensor. P1108 code. The sensor is under the seat in the right hand upper corner of the air filter box. THERE IS NO VACUUM LINES HOOKED TO IT!!!! the only sensor with the hoses your describing is the MAP sensor. So i am suspecting your not checking the right wires. Now once you get that sorted out. And checking for a short between A23 and A01 by utilizing the continuity test amd you do not have continuity I would then say there is no short. Are you testing at the sensor end of the cable ? And if so what if one of them wires is cut again no continuity. I'm suprised they don't habe you check the cable integraty first then a short. But again this is not my cup of tea. Someone like @DEcosse would respond and I would read and learn. Anyway lets first make sure your on the right sensor then we can move on.

 

[Hammer]

Guess it would help if i read everything that i copied and pasted more thoroughly. The MAP sensor is what attaches to the vacuum lines. I've been looking at the wrong sensor.

 

[Hammer]

k, so Ambient air pressure sensor = Barometric pressure sensor?

 

[warp9.9]

Yes but just to make sure you did not have a typo the error code p1108 is ambient pressure sensor high voltage. Which is the barametric pressure sensor. Error code p0108 is the map sensor high voltage. Anyway I took the code looked at the wire schematics and the three wires listed in the code test go to #22 the ambient pressure sensor. Now to make triple sure because the coolant code is p0118 I want to make sure you typed the right code number. If so your on the wrong sensor. For the test.

 

[Hammer]

Yes but just to make sure you did not have a typo the error code p1108 is ambient pressure sensor high voltage. Which is the barametric pressure sensor. Error code p0108 is the map sensor high voltage. Anyway I took the code looked at the wire schematics and the three wires listed in the code test go to #22 the ambient pressure sensor. Now to make triple sure because the coolant code is p0118 I want to make sure you typed the right code number. If so your on the wrong sensor. For the test.

P1108 is the right code.

All 3 wires pinned out fine. Time to look at the sensor itself. Thanks for your help.

 

[DEcosse]

You should also see the actual pressure reading using TuneECU if you have that available to hook up
That value will be in left margin of the Diagnostics page under "barometric" tab
It should be ~ 1000 give or take, depending on your actual local atmospheric condition.
(should read the same as the MAP sensor with engine not running)

I don't quite recall exactly if the connectors are the same for the Ambient and MAP sensors but I believe they are - they are essentially the same transducer with just a mechanical fitment difference; you can try plugging the MAP sensor into the Ambient & vice versa) and see if error tracks the sensor or the connector.
(obviously can't run engine like this but you can get a static reading)

 

[TURBO200R4]

what scanner brand or tunecu ect. did u use to get the manufacture code of p1108 ?
do u have a pcv or other system installed on your rocket?