First time caller....
Just. Bought a 2017 street bob, cable throttle, rode it home yesterday no issues, went to fire it up this arvo and after 30 seconds I am getting a check engine light, it came with a v&h fuelpak 3 so i installed the software on my phone and then checked the codes
Po123 - tps sensor high , when I click on the fault code it tells me the tps is disconnected. Checked the plug and it looks ok. If i power off the ignition and turn the bike on again, i can see the sensor reading fine for 30 seconds then it goes to 100%
Looks like it will be going back to the dealer, but is it ok to ride to the dealer like this? Its about 90kms to get there.
I found a process that says it resets the tps, but no change.
Like I mentioned, if i turn off the ignition and back on , the fuelpak 3 software, New sensors option reads the tps sensor just fine for exactly 30 seconds then throws the check engine light again, seems to idle and respond to the throttle ok tho.
Any other things to try?
Cheers
Tps disconnects after 30 seconds
Re: Tps disconnects after 30 seconds
Welcome welcome.
That behaviour usually isn’t a dead TPS. The fact it reads fine on key-on and then trips after 30 seconds points to a wiring/pin issue at the throttle body rather the sensor itself. Should be fine for the 90km ride if it’s running clean, but there’s a chance it’ll drop into limp mode, just don’t hammer it.
Otherwise if you’re handy with wiring and a multimeter, unplug the TPS and check the pins closely (they love backing out even when they look fine), then check you’ve got a solid 5V reference and ground, and that the TPS signal rises steadily as you slowly open the throttle, starting low at closed and increasing evenly, without sudden jumps or snapping straight to 5V. Also gently flex the harness right at the connector while watching the reading — if it spikes, you’ve found it. If all that checks out, send it back to the dealer.
That behaviour usually isn’t a dead TPS. The fact it reads fine on key-on and then trips after 30 seconds points to a wiring/pin issue at the throttle body rather the sensor itself. Should be fine for the 90km ride if it’s running clean, but there’s a chance it’ll drop into limp mode, just don’t hammer it.
Otherwise if you’re handy with wiring and a multimeter, unplug the TPS and check the pins closely (they love backing out even when they look fine), then check you’ve got a solid 5V reference and ground, and that the TPS signal rises steadily as you slowly open the throttle, starting low at closed and increasing evenly, without sudden jumps or snapping straight to 5V. Also gently flex the harness right at the connector while watching the reading — if it spikes, you’ve found it. If all that checks out, send it back to the dealer.
Re: Tps disconnects after 30 seconds
Had a look into this a bit deeper because the 30 second timing is interesting.
One thing worth knowing on the 2017 Dyna (Delphi ECM, cable throttle) is that the TPS isn’t a “dumb” standalone sensor. The ECM does a plausibility check after startup once it sees RPM, temp input and stable idle. If the TPS voltage is outside expected range relative to idle airflow, it’ll flag P0123 even if the raw signal still looks OK on a scanner.
Two things that commonly cause that delay on these bikes that haven’t been mentioned yet:
1) Throttle stop / idle airflow mismatch
If the throttle blade isn’t fully returning to its mechanical stop (cable too tight, bar risers pulling on it, or sticky throttle cam), the ECM can decide the TPS signal is “too high for closed throttle” once it switches out of startup logic. That happens roughly 20–40 seconds after start. It may be worth backing off the throttle cable adjuster slightly and confirming the blade snaps fully shut.
2) Heat-soak related reference voltage fault
On Dynas of this era, the TPS 5 V reference shares the same internal ECM supply as MAP and IAT. A marginal internal ECM fault or slightly high resistance in the ref/ground circuit can pass key-on tests, then fail once the ECM warms internally. When that happens the TPS often pegs to 100% or shows “disconnected” even though the wiring checks out cold. This behaviour does show up on Delphi systems and won’t always show with a basic wiggle test.
A couple of other points specific to your setup:
Fuelpak FP3 doesn’t alter TPS input or voltage (it’s CAN-bus only), so it’s not causing the fault — it’s just reporting what the ECM is seeing.
AFAIK there is no TPS relearn procedure on cable-throttle Dynas. Any “reset” steps you find online don’t apply to this bike.
Riding it 90 km should be fine if it’s behaving, but if the ECM decides the TPS is implausible it can drop into reduced performance without warning.
Because the throttle-closure check is quick and costs nothing, that’s where I’d start. If it were mine, I’d confirm the throttle blade fully closes with the bars turned lock-to-lock, then slightly loosen throttle cable free play and retest. If the fault still appears at ~30 seconds every time, I’d be strongly suspecting either the throttle body assembly or the ECM rather than the TPS sensor itself.
Given it’s a fresh purchase, dealer diagnosis is likely the right call — but it’s worth mentioning the delayed plausibility check / idle airflow angle to them so they don’t just throw a TPS at it and call it fixed 😉
One thing worth knowing on the 2017 Dyna (Delphi ECM, cable throttle) is that the TPS isn’t a “dumb” standalone sensor. The ECM does a plausibility check after startup once it sees RPM, temp input and stable idle. If the TPS voltage is outside expected range relative to idle airflow, it’ll flag P0123 even if the raw signal still looks OK on a scanner.
Two things that commonly cause that delay on these bikes that haven’t been mentioned yet:
1) Throttle stop / idle airflow mismatch
If the throttle blade isn’t fully returning to its mechanical stop (cable too tight, bar risers pulling on it, or sticky throttle cam), the ECM can decide the TPS signal is “too high for closed throttle” once it switches out of startup logic. That happens roughly 20–40 seconds after start. It may be worth backing off the throttle cable adjuster slightly and confirming the blade snaps fully shut.
2) Heat-soak related reference voltage fault
On Dynas of this era, the TPS 5 V reference shares the same internal ECM supply as MAP and IAT. A marginal internal ECM fault or slightly high resistance in the ref/ground circuit can pass key-on tests, then fail once the ECM warms internally. When that happens the TPS often pegs to 100% or shows “disconnected” even though the wiring checks out cold. This behaviour does show up on Delphi systems and won’t always show with a basic wiggle test.
A couple of other points specific to your setup:
Fuelpak FP3 doesn’t alter TPS input or voltage (it’s CAN-bus only), so it’s not causing the fault — it’s just reporting what the ECM is seeing.
AFAIK there is no TPS relearn procedure on cable-throttle Dynas. Any “reset” steps you find online don’t apply to this bike.
Riding it 90 km should be fine if it’s behaving, but if the ECM decides the TPS is implausible it can drop into reduced performance without warning.
Because the throttle-closure check is quick and costs nothing, that’s where I’d start. If it were mine, I’d confirm the throttle blade fully closes with the bars turned lock-to-lock, then slightly loosen throttle cable free play and retest. If the fault still appears at ~30 seconds every time, I’d be strongly suspecting either the throttle body assembly or the ECM rather than the TPS sensor itself.
Given it’s a fresh purchase, dealer diagnosis is likely the right call — but it’s worth mentioning the delayed plausibility check / idle airflow angle to them so they don’t just throw a TPS at it and call it fixed 😉
Re: Tps disconnects after 30 seconds
Welcome to the forums mate
To supplement the helpful info above, you can also check out Dr. Harley which can provide really useful info to diagnose odd issues like this as well as steps to resolve them
Let us know how you get on!
To supplement the helpful info above, you can also check out Dr. Harley which can provide really useful info to diagnose odd issues like this as well as steps to resolve them
Let us know how you get on!
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Re: Tps disconnects after 30 seconds
Ok turns out this was an issue caused by the Vance and Hines FP3 the bike had a powervision tune on it which got nuked by plugging in the fp3 , got it reflashed by HD and its now all good . FP3 went in the bin to avoid similiar future occurances