Secondary throttle failure

Gruff

.020 Over
Joined
Jul 2, 2016
Messages
19
Location
Rochester, uk
Ride
Rocket 3classic,2008
Hi all.
I am getting error code p0638 secondary throttle failure. All settings are spot on when I look on tuneecu. secondary tps is new. Secondary plates have been removed and also set to 100%. What I have noticed is the secondary tps is trying to close the secondary throttle under spring tension .
I searched on here and Google but have no luck with a fix.
If anyone has any ideas please post.
Many thanks
Gruff
 
Hi all.
I am getting error code p0638 secondary throttle failure. All settings are spot on when I look on tuneecu. secondary tps is new. Secondary plates have been removed and also set to 100%. What I have noticed is the secondary tps is trying to close the secondary throttle under spring tension .
I searched on here and Google but have no luck with a fix.
If anyone has any ideas please post.
Many thanks
Gruff

Hi Gruff, iirc the secondary TPS when fitted correctly does have a little spring on it trying to open the secondary butterflies.
Whereas the primary TPS is installed to be setup the opposite, the spring in it tries to close the primary butterflies.

I had this error P0638 before, the fix for my particular issue is illustrated in this video
I hope yours is the same as you can't buy the secondary stepper motor alone (new at least) as it comes as part of the throttle body $$$$

 
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Yep the secondary TPS is not a straight install like the primary TPS you have to hold the secondary throttle plates and thus shaft open while installing the secondary TPS hopefully you have not damaged the tabs that the throttle shaft uses.
 
Thanks for the swift response.
I installed the secondary tps as per the manual and all voltages are correct,the tps is intact luckily. I will give the instructions in your video a try tomorrow. I will let you know how I get on
Thanks
Gruff
 
I had the same problem as you. Set the TPS voltage on the closed body position (as directed in the maintenance manual) and got the error code. Here is what I did to cure this problem: First, don't worry about the TPS voltage as the computer gets low end and high end voltage during the throttle body sweep and uses this for setting open and closed (and all) throttle positions. Unplug the secondary motor, turn key to run, loosen the bolt on the secondary TPS, manually move the secondary throttle plates full open to full closed (might have to reinstall one plate to open and close shafts) and adjust the TPS sensor to ensure the range of the throttle plate(s) (open to closed) are within the limits of the TPS. Once adjusted within the TPS limits, snug down the TPS sensor bolt. If you cannot get the plate(s) within the TPS range, you have incorrectly installed the TPS and must reinstall it. Once all is done, turn key off, plug secondary in, turn key back on and you'll find it sweeps as it should and buzzing in secondary motor will be gone. Also no error code. Did mine last year and have had no problem even with the secondary plates removed.
 
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O.K. Changing the subject slightly here (as we do!)
I'd removed the secondary butterflies some time ago.
Now (on a spare throttle body assy) I've removed the secondary throttle shaft, motor and TPS, and have plugged the shaft holes.
Now I have no doubt that this will throw up a code saying bits aren't there/working.
What can I do to prevent/eliminate this ?

20180402_074853.jpg
 
O.K. Changing the subject slightly here (as we do!)
I'd removed the secondary butterflies some time ago.
Now (on a spare throttle body assy) I've removed the secondary throttle shaft, motor and TPS, and have plugged the shaft holes.
Now I have no doubt that this will throw up a code saying bits aren't there/working.
What can I do to prevent/eliminate this ?

20180402_074853.jpg
OK, how did you plug up the shaft holes in the throttle bodies (looks really good)? It would seem someone on this site could come up with a way to rig the TPS to the secondary throttle motor (so it fools the ECM) and hid it somewhere! Claviger, this is right up your ally!
 
O.K. Changing the subject slightly here (as we do!)
I'd removed the secondary butterflies some time ago.
Now (on a spare throttle body assy) I've removed the secondary throttle shaft, motor and TPS, and have plugged the shaft holes.
Now I have no doubt that this will throw up a code saying bits aren't there/working.
What can I do to prevent/eliminate this ?

20180402_074853.jpg
As the famous Warp9.999 would say ---stick some black tape on it:D
 
Hmm can one hook the tps to the secondary throttle motor and stuff it under the tank even if you needed to make a little aluminum mounting plate. With the secondarys gone you could set each gear opening to 0% then the motor would only actuate during the start up test. Just thinking out loud here.
 
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