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DTC 8-1 TP (Throttle Position) sensor low voltage
With ignition switch on and stop/run on, probe sensor contacts to verify steady voltage increase from throttle fully closed to throttle fully open.
Can you please explain "probe sensor contacts"? I assume the TPS is plugged in for this test, and I use a safety pin to access a metallic contact point at the connection with my VOM, but what two contact points do I connect my VOM leads to? The FSM states "Check the TPS with the Motorcycle Communication System (MCS) with the throttle fully closed. I assume that my VOM can take the place of the MCS?
Thank you.[/b]
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Hi Dave, have a look at this post;
http://cb1100forum.com/forum/showthread....#pid189679
opened safety pin should give you good contact once it bottoms out inside the connector, you could measure all three and write down the results.
left wire..................volts
middle wire..............volts
right wire..................volts
Positive probe on the safety pin wire, negative probe to good ground, not the throttle body itself.
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(01-22-2018, 01:34 PM)max_imp Wrote: Hi Dave, have a look at this post;
http://cb1100forum.com/forum/showthread....#pid189679
opened safety pin should give you good contact once it bottoms out inside the connector, you could measure all three and write down the results.
left wire..................volts
middle wire..............volts
right wire..................volts
Positive probe on the safety pin wire, negative probe to good ground, not the throttle body itself. Thank you very much Max - I missed this post.
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That's cool, mate, i'll work with you because it gets to be a task to find all the scattered info on here.
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Here are the results of my TPS test:
Test #1: Sensor fully connected, ignition switch on, kill switch on, measured voltage between sensor wires and battery negative terminal. (It was impossible to find a reliable ground anywhere on the bike, except at the battery).
1. Red/Yellow: Throttle fully closed = 4.8 VDC. Throttle fully open = no change.
2. Red/Black; Throttle fully closed = .5 VDC. Throttle fully open = 4.4 VDC.
3. Green/Black: Throttle fully closed = 0.0 VDC. Throttle open = 0.0 VDC.
Test #2: Sensor disconnected, ignition switch on, kill switch on, measured voltage between sensor wires and battery negative terminal. Throttle position not applicable with sensor disconnected.
1. Red/Yellow = 4.8 VDC.
2. Red/Black = 0.0 VDC.
3. Green/Black= 0.0 VDC.
I was not able to measure the resistance of the TPS while it is mounted on the bike because the pin connectors are nearly impossible to see, and nearly impossible to make contact with. Ideally, a plug-in connector with loose wires would be the hot set-up, but maybe if I use a mirror and a second pair of hands I may be able to do it – just not tonight.
All connections between the TPS and the harness appeared good, with no looseness or corrosion. I unplugged and reconnected the TPS connector at least a dozen times during my tests, so if there was a loose connection that was not obvious it is most-likely not loose anymore.
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Thanks Dave, that is a very complete set of results, put very clearly and i'm sure doc will appreciate them and get back to you.
max
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(01-22-2018, 04:37 PM)max_imp Wrote: Thanks Dave, that is a very complete set of results, put very clearly and i'm sure doc will appreciate them and get back to you.
max Thank YOU Max, and Sportsterdoc also! I'll try to put some miles on the bike tonight with the TPS unplugged. I'll brave the extreme cold here in S.Ca for the sake of science (temps are in the low 50 degrees in the evening now). I hope that my disconnecting and reconnecting the TPS so many times, and poking the wires with a needle, didn't change anything that will alter the results.
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Dave
Thank you much for being such a willing guinea pig!
I sent a draft response to Max, for his input.
Meanwhile, please probe the black/green wire at the TPS connector (unplugged would be best) and read resistance to battery negative post.
I'd expect <0.1 ohm
As for sensor readings, when unplugged, without removing the TPS:
Looking at the disconnected sensor, with locking tab up:
Left: black/yellow 5 VDC power
Center: black/red signal output (resistance between this and black/green ground should be 1.5 K ohms to 0.5 K ohms...open and close throttle while ohmmeter connected...using your third hand!) Based upon your black/red signal readings, I'd expect you to see these resistance values, with a smooth change as throttle moves. This is an alternate to the output signal test of 0.5 to 4.5 VDC.
Right: black/green ground
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Bottom line is that readings are normal.
FYI re color names: First color is sold/second color is stripe
From the Honda FSM I am referencing, colors are black/yellow = power, black/red = signal and black/green = ground at the TPS connector. I am not aware if there is a difference for model years.
Comments on your tests:
Power on, sensor connected:
1. Red/Yellow should be black/yellow (power) : Throttle fully closed = 4.8 VDC. Throttle fully open = no change (normal 4.75 to 5.25)
2. Red/Black should be black/red (output signal): Throttle fully closed = .5 VDC. Throttle fully open = 4.4 VDC. (normal 0.5 to 4.5, with smooth transition)
3. Green/Black should be black/green (ground): 0 vdc (not a FSM test.
Power on, sensor disconnected
1. Red/Yellow should be black/yellow = 4.8 VDC. (normal 4.75 to 5.25)
2. Red/Black should be black/red = 0.0 VDC (normal)
3. Green/Black= 0.0 VDC (normal)
Next steps, before discounting TPS as an issue:
B & C (key off) are getting more involved and not as easy to access.
A. Measure resistance of ground wire black/green (pin 1 [left] facing connector with locking tab up) in connector, to battery negative post.
B. Measure resistance of power wire black/yellow (pin 3), which leaves the 10 pin connector as yellow/red to ECM A9
C. Measure resistance of signal black/red Pin 2-center), which leaves the 10 pin connector as red/yellow to ECM B17
If resistances are about 0.1 ohm, then a TPS issue would be dismissed.
You may not be excited about doing B & C and I am not pushing you, but the number of electrical issues I have found (direct and remote) due to broken/partially broken wires and loose connections over the years has been rather high.
If you choose to pass, I am inclined to start checking out the IACV, next.
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Doc - thank you for all your help. I will do my best to perform all he tests you have described, I just can't do it tonight, or tomorrow either. Concerning the wire colors: I was working in my garage, underneath a fluorescent light, so either my eyes are worse than I think, or the light was playing tricks on me. I will double-check the wire colors when I repeat the tests. I will need help performing any measurements on the unplugged sensor because I can't even see the leads inside of it. I am assuming that if I use a mirror, and get somebody to help me, then I might be able to make these measurements. Thanks again for all your support.
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