P0638 Diagnostic Code

[tdragger]

I've been getting a sporadic ECM Code P0638 on my '06 Std. The manual says "2nd Throttle Circuit Malfunction". The bike runs fine and doesn't go into "limp" mode. ECM Light goes out after 3 warm up cycles.

Can any of you mechanical minded folks shed some light on this?

 

[tdragger]

28 views and no one has any idea?

geez...this is going to be fun trying to figure this out on my own.

 

[HeR3tic]

Allow me to guess: Throttle Position Sensor for secondaries.
Do you have a TuneBoy? If so, do you run 100% open secondaries?
I've yet to dink with TPS positioning to tweak the voltage as required. It's on my tadu list. Is there a faulty plug connection to the secondary sensor?

 

[tdragger]

No Tuneboy. All the serious mechanicals are stock except for Staintune pipes and cat box replacement.

 

[Toystoretom]

Without doing any research I would guess that what it is talking about are the secondary throttle plates and the actuator that controls them. This would mean that you probably have an intermittent open or short in the harness for that system. There is at least one connector at the actuator for the secondary throttle plates and I would start there. Take the connector apart, inspect it to make sure none of the little female ends have been pushed into the plug and that it is clean and not full of crud or corrosion. I would tweak the pins in the actuator just a tad and maybe squeeze the female sockets in the plug just a little. You might hit an auto parts store and see if they have some electrical connector enhancer (which is different than di-electric grease). If you can't find the enhancer use di electric grease anyway, it will protect the connectors and help the plug snap back together.

Go out and ride and see if that fixes it. If not you may have to follow that harness backwards. That whole engine control harness is actually a large subharness and there is a rather large connector that you may have to check. Refer to your shop manual and the wiring diagram. Also, it could be a pin problem at the ECM.

After fixing those connections and if you still have the problem I would do a continuity check on the wires involved. Once again check your service manual for the color codes. Pin one wire right at the ECM and then pin the same wire at the secondary throttle plate actuator. Be careful cause the wires may change color code as they go through the harness, once again study the wiring diagram to confirm this. After pinning the wires hook a DVOM to them and set it on continuity and wiggle the **** out of the wire harness everywhere between the ECM and the actuator and see if you loose continuity. Do this with all the wires. If you do loose continuity you will either have to jump that wire or split open the harness until you find the break.

If that shows nothing then pin one of the wires and hook your DVOM to that and the other lead to a good ground and start wiggling again. If you find continuity then you have a short to ground.

Nothin' to this **** and that's why you didn't get any replies....

 

[Pig9r]

tdragger- I was 1 of the 28....I didn't want to guess because then someone like Tom comes along and gives a way better answer than I could have.

 

[tdragger]

Thanks, Tom. That's the type of expertise this board is known for. I've never worked with FI systems so I don't want to tear into it without a little guidance.

Ok, so the throttle bodies have a sensor on each of the primary and secondary butterflies. I assume that the folks that have removed the secondaries have somehow told the ECM to ignore the secondary sensors.

Would an improperly adjusted throttle cable throw a sensor out of range?

 

[Pig9r]

The primary and secondary butterflies have stepper motors that control their operation. Check the connectors to those as Tom explained. When the secondaries are removed there is no sensor that needs to be bypassed, the stepper motor works as directed it's just there are no plates on the rod.

 

[HeR3tic]

...Ok, so the throttle bodies have a sensor on each of the primary and secondary butterflies. I assume that the folks that have removed the secondaries have somehow told the ECM to ignore the secondary sensors...

Having not seen a response in 28 views I simply was throwing out inquiries. Just so you'd know someone out there in cyber space was listening

The ole lady rattles on about god knows what; if I grunt she knows that I'm at least acknowledging her presence

The last time she got to ragging about my not listening I apologized, "I'm sorry I wasn't listening...would you mind repeating everything since we got married"