Finally got my speedo reading correctly after fitting 265/70/R17s so I though I would give something back to the PP community and share my experience.
After upgrading the tyres to some nice new Cooper S/T Maxx, I began looking for a way to recalibrate the speedo to compensate for the larger tyre diameter. Like many fellow PradoPointers running 265/70/R17s I found my speedo reading under by around 5%. To my surprise I found most people were happy to tolerate the error, but after my latest impromptu meeting with the kind folk of the WA police force, I decided to get serious about getting it sorted. With the new tyres my speedo was reading 105kph when my true speed was 110kph
Having not had too much luck on PP I consulted the google box, which again didn't really help too much. Eventually I stumbled across a bloke in the states with a 4runner who found a nice solution. He used the SpeedoHealer from www.healtech-electronics.com. It's basically a gizmo that tweaks the speed pulses coming from the speed sensor before the signal is sent to the display. For Toyota's with ABS, traction and stability control, there are speed sensors in each wheel that are fed back to the Skid Control ECU which then combines them all into a single speed signal that is sent to the combination meter (speedometer) in the dash. The trick is to tap into this signal and let the speedohealer work its magic on it. So, I figured I would give it a go and ordered the gadget. They are designed for motorcycles but they offer a universal wiring harness which is what I went for.
From what I’ve seen there are a few different brands available that can do this. I think any of the electrical speedo correction devices will work, the key is putting it in the right place. After digging up some electrical schematics I found the easiest place to hack into the signal was at pin 5 of connector IL1 which is located on the passenger side on the left hand side of the aircon filter behind the glove box.
First remove the wood grain (or equivalent) insert thingy. I don’t think it’s absolutely necessary but it makes it easier to see the glovebox retainer clips. It's just held in with snap in clips so just pull it out gently:
Now remove the 5(?) screws holding in the glove box surround and remove it, there are a couple of plugs that need to be disconnected from the glovebox in the process:
To be continued; image limit reached...
After upgrading the tyres to some nice new Cooper S/T Maxx, I began looking for a way to recalibrate the speedo to compensate for the larger tyre diameter. Like many fellow PradoPointers running 265/70/R17s I found my speedo reading under by around 5%. To my surprise I found most people were happy to tolerate the error, but after my latest impromptu meeting with the kind folk of the WA police force, I decided to get serious about getting it sorted. With the new tyres my speedo was reading 105kph when my true speed was 110kph
Having not had too much luck on PP I consulted the google box, which again didn't really help too much. Eventually I stumbled across a bloke in the states with a 4runner who found a nice solution. He used the SpeedoHealer from www.healtech-electronics.com. It's basically a gizmo that tweaks the speed pulses coming from the speed sensor before the signal is sent to the display. For Toyota's with ABS, traction and stability control, there are speed sensors in each wheel that are fed back to the Skid Control ECU which then combines them all into a single speed signal that is sent to the combination meter (speedometer) in the dash. The trick is to tap into this signal and let the speedohealer work its magic on it. So, I figured I would give it a go and ordered the gadget. They are designed for motorcycles but they offer a universal wiring harness which is what I went for.
From what I’ve seen there are a few different brands available that can do this. I think any of the electrical speedo correction devices will work, the key is putting it in the right place. After digging up some electrical schematics I found the easiest place to hack into the signal was at pin 5 of connector IL1 which is located on the passenger side on the left hand side of the aircon filter behind the glove box.
First remove the wood grain (or equivalent) insert thingy. I don’t think it’s absolutely necessary but it makes it easier to see the glovebox retainer clips. It's just held in with snap in clips so just pull it out gently:
Now remove the 5(?) screws holding in the glove box surround and remove it, there are a couple of plugs that need to be disconnected from the glovebox in the process:
To be continued; image limit reached...
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