Convert mechanical speedometer to electronic speedo?

[mickburkesnr]

This relates to my Toyota Corolla E11.

I'm currently hunting around for a vehicle speed sensor, and the two guys I've had any luck with have either snapped it off in front of me or have said that they're struggling to get it off. This VSS bolts on to the gearbox, so can be a pain to take off aparently.

Thing is, my one needs changing. To make matters a bit more complicated, both of these guys were offering the VSS that would be used for an electronic speedometer which the newer vehicles had. Mine doesn't use one of these, it uses the old mechanical speedometer.

I'm just thinking of alternatives at the moment in case I can't get hold of a mechanical VSS. So I'm wondering could I instead "upgrade" it and use an electronic VSS instead? I know these have electrical cables going to them instead of a mechanical one, and I would need to upgrade the dashboard cluster in order to use it. But how difficult could it be? Would it be a case of taking out the mechanical speedometer cable and old dashboard cluster and just replacing it with wires coming from the new VSS to a new dashboard cluster?

[oldcodger]

Hmmm... think I must be getting too old as finding your post a bit hard to follow...

 

What parts have actually gone, your speedo cable or your speedo dial  or both ?

Quote

the two guys I've had any luck with have either snapped it off in front of me or have said that they're struggling to get it off. This VSS bolts on to the gearbox, so can be a pain to take off aparently.

Do you mean they have taken  yours off and broken the cable and / or gearbox part  ?

Any reason you cannot just replace the cable with a new one from Toyota ?

On my later model with the electronic speedo dial I believe the signal comes from part of the ABS system, certainly not the gearbox as I have had that out on mine.

Have to ask if there ever was a model with an electronic speedo dial  driven from the gearbox ?  and if so the retro fit cable with a mechnaical to electronic converter might be rather expensive ..? 

Have you checked with your local Mr. T for prices or info  ?  or you could ask Kingo / Parts King  in the forum...

 

 

[mickburkesnr]

On 28/02/2017 at 5:29 PM, oldcodger said:

Hmmm... think I must be getting too old as finding your post a bit hard to follow...

No, you're not getting too old. I can't handle staying up all night working like I used to. The post isn't my finest bit of writing to be honest!

The story goes that on one of the Facebook groups I asked the question whether anyone had the VSS for my Corolla. This came on the back of an argument I had with my dealership who were adamant I had 4 speed sensors on the car, one on each wheel. They wouldn't accept/listen to me that the sensor I was concerned with existed on the top of the gearbox. Anyway, someone who wasn't too far away from where I work said they had one. I went to their place, they forgot about me coming and spent the next hour trying and struggling to get the part off a donor car - oh and I only have a 30 minute lunch break! He's trying his best, but ends up snapping the top off of the VSS. So it was an hour waiting for nothing, and so far he hasn't rang me back to tell me he's got another replacement.

I've since spoken to a guy in Cork and he said he has one. But there are two types, one's mechanical for use with mechanical speedometers (like mine) and one for use with electronic speedometers. The electronic one he has a few of and they're all off the car. The one mechanical version he has is still stuck on the gearbox.

I had always considered that the speedometer, electronic ones anyway, got their speed from either the ECU or the gearbox. The four speed sensors on the wheels were just meant for making sure none of the wheels lock up in an ABS system. I have a friend who has a speed sensor problem one of his wheels on his Peugeot and his speedometer works fine. It just moans about the problem.

In terms of what's actually broken, I've no idea. I have a replacement speedo cable, but I wanted to change the VSS first and see if that fixed the problem. Basically start at the root of the chain and work up to the dashboard. Plus I've an engine warning light that comes on which indicates that the car doesn't know how fast it's going.

I will see how the Cork guy comes through to me and after which I'll give Parts King a ring.

[mickburkesnr]

Right, this isn't looking at all good!

The guy from Cork said he couldn't get the bit I need without basically breaking it the sensor itself. I've tried to take mine off with some persuasion but you really can't move something that's been fused for nearly 20 years without problems! Plus I can't find a second hand replacement mechanical VSS anywhere, which I'm not surprised by really.

That said, God doesn't shut a door without opening a window. I'm looking more closely at the electronic VSS swap, I think it can be done. New speedo is required, maybe even a new instrument panel. But I think more than ever now it can definately be done. 

Before falling asleep the other night I thought about whether to make this an opportunity for some cool modifications. Basically replace the instrument cluster altogehter, replace the speedo with an LCD screen driven by a computer which would get its signals from the new VSS. Basically make the dashboard look a bit like Knight Rider. 

The car is cheap enough for me to throw it away, so if I try this modification and I end up blowing the car up then I can sell Paddy for scrap. If it works out, then I can tell how fast I'm going and pass an MOT!

[oldcodger]

Didn't Kingo/ Parts King come up with a part number / price for you  ?   might cost, but surely a simpler option ?

If you give him or Toyota  your Reg  and Chassis number don't see how they cannot come up with the right part, unless you have had an engine change ?

 

Changing to an electronic sensor, does that not feed into the ECM ?  would your EMC handle that ?

 

Read this bit from a Haynes Engine Management manual  re 92 - 97 4AFE corollas.

" VSS is used to advise ECM of vehicle speed.

Early models generate an AC signal which the ECM converts to a digital value.

Some later models have a Hall Effect VSS which produces a square wave and is mounted on the  speeedometer and is driven by the speedo cable.

The VSS returns a square wave to the ECM "

[mickburkesnr]

He did, it's the plastic gear that was quoted but I'm on about the casing itself. The gear itself is £30-odd. My worry is the sensor itself, I've sent him a message about this as well and waiting for a price. The electrical version doesn't cost very much at all.

Not sure if that's applicable as mine has a 4E-FE engine. It's not difficult, I don't think, to convert the electrical signal given by the VSS to be something the ECU is expecting. From what I've read the ECU gets the speed from the dashboard instrument thing, so if I wanted to keep things basic I could use the electrical VSS to spin a motor that spins the mechanical speedo.