Speedo needle dead, P1500 error code, odometer works fine

[TURBO200R4]

I use a garmin for speed and miles.
There has been a few that had bad speedosq.
I seem to recall a thread about using a different speedo.

 

[ChrisACT]

P1500 is a Vehicle speed output circuit malfunction
P0500 is a Vehicle speed sensor malfunction.

So my problem isn't the sensor. It's on the output side of the ECU. Either the ECU itself, the wiring loom or the speedo.

 

[ChrisACT]

And I just found this thread: Pre-start issues

He had exactly the same symptoms as me and it was the speedo. Bugger.

 

[ChrisACT]

Given the price of them ... perhaps aftermarket is the go.

Acewell ACE-44xx looks like it has the features I want. About half the price of the OEM speedo.

I've read here that some have had issues with Acewell units but I might give it a go anyway. The Daytona and Koso stuff doesn't do it for me.

ACE-4000 sereis Multi-Function Speedometer, with Digital LCD Display and needle gauge

Interestingly, the Acewell should work with the stock speedo output from the Triumph ECU. It'll handle up to 7,000 pulses per second for the speed input (up to 199 pulses per wheel revolution and wheels up to 3,999mm circumference). I think I read that the Rocket ECU puts out 48 pulses per wheel revolution so unless I manage to get the old girl up to Mach 0.9 ... it should handle it.

Acewell Cross Reference

I can replace both gauges this way and perhaps find some space behind the fly screen for my GPS so it doesn't keep getting splattered with bugs.

 

[ChrisACT]

Speedo arrived. Less than 48 hours after I ordered it. Can't do much better than that.

I've also ordered an Oscilloscope so I can check out what signals are coming out of the ECU as far as tacho and speedo goes. That should arrive within the week. I've read the other threads on here about it so we'll see how that goes getting it all to work. May need a pull up or pull down resistor on those wires.
Worst case scenario, I just plug the tach wire into the coil and use the included magnetic speedo sensor. But if I can get it to work with the existing loom I'll document how I did it here so everyone else can know how to make Acewell gauges work on the old Rockets.
The tricky bit might actually be mounting it in a tidy and factory (ish) looking manner.

 

[ChrisACT]

So ... an update.

I've finally gotten around to working on this problem.
I raised the back end off the ground, started her up and ran it in gear so the rear tyre is spinning.
I got no signal out of the ECU on the speed signal wire so I thought I'd see if I could get anything directly off the road speed sensor. All I got out of it was 5V DC. No square wave at all on the pink wire.
TuneECU shows 0kmh no matter how fast the rear wheel is spinning. In retrospect, I should've checked that first.
So after all that, I'm thinking the road speed sensor is stuffed.

I presume this is the little bugger hiding behind the sidestand:

On the bright side, I worked out what the signal is on the tacho signal wire.

12V DC when you turn the ignition on then 0 - 12V square wave once engine fires
80ms between pulses (12.5Hz) at 750RPM so 1 cycle per revolution of the crank
I'm not sure if the 12VDC is supplied by the tacho and the ECU just pulls it down to 0V or if the ECU is sending the full signal itself. I didn't want to cut that wire until I've confirmed I'm going to replace the gauges.
If the speed sensor is the only problem then I'll retain the stock clocks. If I can get my hands on another loom for the gauges, I'll cut it and find out where the DC is coming from.

 

[TURBO200R4]

I have never checked the rocket
All the speed sensors i have seen produces ac voltage it can be measured with a scope. Several maybe 15 to 30 per revalution.
The ecu does not furnish power it reads the ac pulses.
I have never heard of the vss going bad on a rocket but i see a few go bad because of the magnetic pulls of the magnet inside the sensor loosens the magnet or breaks the wires.
Also u can check with an ohm meter but not as good as a scope
Hth
Ps sometimes because it is a magnet it will be covered with metal causing failure.

 

[ChrisACT]

I have never checked the rocket
All the speed sensors i have seen produces ac voltage it can be measured with a scope. Several maybe 15 to 30 per revalution.
The ecu does not furnish power it reads the ac pulses.
I have never heard of the vss going bad on a rocket but i see a few go bad because of the magnetic pulls of the magnet inside the sensor loosens the magnet or breaks the wires.
Also u can check with an ohm meter but not as good as a scope
Hth
Ps sometimes because it is a magnet it will be covered with metal causing failure.

I am using a scope for all measurements.

The speed sensor is not open circuit because I get 5VDC out of it between the pink (signal) and black/white (ground) wires. When the rear wheel is spinning, there should be a square wave, presumably from 0 - 5V.

EDIT: perhaps it's not quite as simple as I thought. I haven't measured the voltage on the Orange/Red wire which is supply voltage from the speedo. Perhaps that is dead and therefore the speed sensor won't produce a signal. Although if that is so, where is the 5VDC coming from on the signal wire? The ECU?

EDIT again: Yep, the ECU provides the 5VDC.

You could be right about the magnet though.

Can the speed sensor be removed without draining the oil? Or will oil pour out of the hole if I do that?

Edit: No, oil does not go everywhere. Can be removed no problem without draining oil.

One other possible issue I found is that the driveline lash with the rear wheel off the ground is really noisy. I'm worried there's a problem there now too.

 

[ChrisACT]

OK, I've pulled the sensor and there was nothing on it except some oil. It's still magnetic and looks in good order physically.
I hooked it up again but with the sensor out of the engine, switched the ignition on and immediately got the 5VDC again on the pink wire.
I waved a spanner in front of it to the extent that I could feel the sensor pulling on the spanner, even touching it and got no signal out of it at all.

Then I disconnected the sensor and measured the resistance across the terminals:
Black/white to pink - 24Mohm
Black/white to Orange/Red - 34Mohm
Pink to Orange/Red - open (or higher than my DMM could measure. Effectively open circuit.

Has anyone else ever measured their road speed sensor? If so, how did your results compare to mine?

 

[ChrisACT]

Ugggh ... speedo wasn't plugged into the loom. Hence no power to the speed sensor from the speedo.

After I plug it back in ...

The ECU is supplying 5VDC to the sensor on the pink wire (signal)
The speedo is supplying 12VDC to the Orange/Red wire (speedo power supply)

BUT!!!!

When I disconnected the sensor and reconnected the speedo then switched on the ignition, both the speedo and tacho did their startup cycle.

Reconnect the road speed sensor and speedo is dead again.

That means the speedo works and it's definitely the sensor. Presumably the ECU kills the speedo when it has the P1500 error code. Would love to know how the odometer was working if in fact the sensor is the issue.

So now, to order a new road speed sensor and reinstall the stock clocks back on the bike.