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Pottsy · 22nd September 2007, 21:54

This article will show you how to remove the built in speedo error. The speedo over-reads by about 5% to 9%, so that any shape or variation in tyre size fitted will always show an over-read, so Honda can never get into legal problems if you are caught speeding when your speedo says you are not.

Difficulty:

Pretty easy. Nuts and bolts, bit of wire stripping and soldering. Should take about an hour.

Ingredients:

A Speedo Healer. This £57 device is a tiny little computer normally fitted to motorcycles that takes the pulses from the speed sensor, and sends slightly slower pulses to the car. It is a mature product, that works well and is transparent in operation.

Socket set, 10mm spanner, wire cutters, soldering iron and solder.

Instructions:

Firstly measure the speedo error using your preferred method. Make sure it's accurate! I used a collection of GPS readings, including the one shown on cars with satnav. I found that if using a flat road and cruise control to keep a steady speed, then it's best to use fourth gear (not sixth), to give the car better control of the speed.

sh_before.jpg

Take out the car keys and put them in your pocket.

Remove the battery clamp, the negative battery terminal and then the positive battery terminal. Lift out the battery using the handles and then pull out the plastic battery holder.

sha1.jpg

Remove the bolt that hold the air filter box to the battery support shelf:

sha2.jpg

Remove the 6 12mm bolts that hold the battery support shelf and whip out the shelf:

sha3.jpg

At the front of the gearbox you'll find the speed sensor plug and socket. The plug is released by pressing in a catch, and it can then be unplugged.

I also unclipped the little bit of loom to allow me to get the plug nice and high for soldering work.

sha4.jpg

Trim back the loom black tape and tube, and then cut the blue/white wire (blue/black on 1.8 cars).

shb1.jpg

The Speedo Healer (SH) comes with its own 4 wire loom. Strip off the red casing for most of the length and leave the red and black wires. Shorten the green and white wires so they will go from the socket on the gearbox to the place you are going to mount the SH.

Put a heat shrink tube (included) onto both the green and white wires.

Strip the two ends of the blue/white wires - solder the SH green wire to the end that goes to the loom, and solder the SH white wire to the short end that goes to the speed sensor plug.

Shrink the tubes over the joints (using a lighter) and tape the whole area up again.

Plug in the plug.

shb2.jpg

Attach the black wire on the SH loom to a suitable earth. I shortened the wires, tinned the end and when putting back the battery support shelf, used one of those bolts:

shb3.jpg

Open up the fuse box and pull out the grey relay shown.

It's tricky to remove. You mustn't use pliers, because these may damage it. Just use fingers, and pull it out while rocking it a bit.

Poke the red wire from the SH loom into the bottom right hole (trim the wire a bit, and make sure no strands poke out - the wire mustn't interfere with the other relay connections) and push the relay back in.

shb4.jpg

Fit an inline fuse to that wire, and cut a little exit hole for it in the fuse box:

shb5.jpg

I then attached the SH to the front of the air filter box using the supplied velcro (having degreased the surfaces). It's good to have the velcro and a bit of spare wire, so you can move the SH for easier programming.

shb6.jpg

Next, use the online calculator to generate instructions on how to program the SH.

Go for a drive! I can see no difference in the operation of the car speedo, except that it's now accurate.

Notes:

This how to has been done on a diesel - the 1.8 may be slightly different.

SH recommend keeping the SH wires away from other loom wires, and mounting the SH away from other electronics.

It's probably best to recalibrate every time you change your tyres. Different tyres (even of supposedly the same size) will in fact be different sizes.

As a tyre wears, the speedo will start to over-read. From new to worn, this change corresponds to 1 mph total at 70 mph.

Because you are removing (say) 6% of the speed pulses, your odometer will accumulate miles at a rate reduced by 6%, and your mpg readout on the computer will also be reduced by 6% (and will probably end up being accurate!!)

Speedo Healer: distributors, bike tutorials, testimonials.

And thanks to Norbert at Speedo Healer for his great help in researching and helping with this little project.

22nd September 2007, 21:54	#1 (permalink)
Pottsy Administrator Civinfo master Join Date: 10th April 2006 Location: Leics Posts: 5,486 Thanks: 22 Thanked 170 Times in 100 Posts iTrader: (0)	Calibrate the speedo This article will show you how to remove the built in speedo error. The speedo over-reads by about 5% to 9%, so that any shape or variation in tyre size fitted will always show an over-read, so Honda can never get into legal problems if you are caught speeding when your speedo says you are not. Difficulty: Pretty easy. Nuts and bolts, bit of wire stripping and soldering. Should take about an hour. Ingredients: A Speedo Healer. This £57 device is a tiny little computer normally fitted to motorcycles that takes the pulses from the speed sensor, and sends slightly slower pulses to the car. It is a mature product, that works well and is transparent in operation. Socket set, 10mm spanner, wire cutters, soldering iron and solder. Instructions: Firstly measure the speedo error using your preferred method. Make sure it's accurate! I used a collection of GPS readings, including the one shown on cars with satnav. I found that if using a flat road and cruise control to keep a steady speed, then it's best to use fourth gear (not sixth), to give the car better control of the speed. sh_before.jpg Take out the car keys and put them in your pocket. Remove the battery clamp, the negative battery terminal and then the positive battery terminal. Lift out the battery using the handles and then pull out the plastic battery holder. sha1.jpg Remove the bolt that hold the air filter box to the battery support shelf: sha2.jpg Remove the 6 12mm bolts that hold the battery support shelf and whip out the shelf: sha3.jpg At the front of the gearbox you'll find the speed sensor plug and socket. The plug is released by pressing in a catch, and it can then be unplugged. I also unclipped the little bit of loom to allow me to get the plug nice and high for soldering work. sha4.jpg Trim back the loom black tape and tube, and then cut the blue/white wire (blue/black on 1.8 cars). shb1.jpg The Speedo Healer (SH) comes with its own 4 wire loom. Strip off the red casing for most of the length and leave the red and black wires. Shorten the green and white wires so they will go from the socket on the gearbox to the place you are going to mount the SH. Put a heat shrink tube (included) onto both the green and white wires. Strip the two ends of the blue/white wires - solder the SH green wire to the end that goes to the loom, and solder the SH white wire to the short end that goes to the speed sensor plug. Shrink the tubes over the joints (using a lighter) and tape the whole area up again. Plug in the plug. shb2.jpg Attach the black wire on the SH loom to a suitable earth. I shortened the wires, tinned the end and when putting back the battery support shelf, used one of those bolts: shb3.jpg Open up the fuse box and pull out the grey relay shown. It's tricky to remove. You mustn't use pliers, because these may damage it. Just use fingers, and pull it out while rocking it a bit. Poke the red wire from the SH loom into the bottom right hole (trim the wire a bit, and make sure no strands poke out - the wire mustn't interfere with the other relay connections) and push the relay back in. shb4.jpg Fit an inline fuse to that wire, and cut a little exit hole for it in the fuse box: shb5.jpg I then attached the SH to the front of the air filter box using the supplied velcro (having degreased the surfaces). It's good to have the velcro and a bit of spare wire, so you can move the SH for easier programming. shb6.jpg Next, use the online calculator to generate instructions on how to program the SH. Go for a drive! I can see no difference in the operation of the car speedo, except that it's now accurate. Notes: This how to has been done on a diesel - the 1.8 may be slightly different. SH recommend keeping the SH wires away from other loom wires, and mounting the SH away from other electronics. It's probably best to recalibrate every time you change your tyres. Different tyres (even of supposedly the same size) will in fact be different sizes. As a tyre wears, the speedo will start to over-read. From new to worn, this change corresponds to 1 mph total at 70 mph. Because you are removing (say) 6% of the speed pulses, your odometer will accumulate miles at a rate reduced by 6%, and your mpg readout on the computer will also be reduced by 6% (and will probably end up being accurate!!) Speedo Healer: distributors, bike tutorials, testimonials. And thanks to Norbert at Speedo Healer for his great help in researching and helping with this little project.