Thread: Speedo.

The Mrs speedo hasn't worked for a long time.
last time I had a go as fixing it, I placed a wanted ad here, and bought a replacement speed sensor off another member. (With a good feedback score)
So I fitted the replacement part, and went for a drive. Speedo still didn't go. I pm'd the seller, who promised me the part was good, and that I should check the wiring had no breaks between the plug, and where-ever the wires go. (But he wasn't able to offer a link to a diagram I could use to do so)
Since then, the speedo has worked sometimes on and off. Oddly on a long trip the speedo seems to work a bit more?

Anyway, this BS has gone on for far too long. I need to fix it for sanities sake. (And cos we don't know how many kms the car has done for servicing purposes, and the Vtec hasn't worked for ages either)

So, can one of you fine people please tell me how to either test the speed sensor, or post a wiring diagram for an EF8 CRX with B16a engine.
Or is it possible that the gauge cluster itself is faulty?
Even better, does someone on Christchurch have a speed sensor I could test fit just to see if that fixes it?
I'm a fairly patient kind of guy, but working on this car does my head in something awful. I think my hands are too big for working on hondas.

That its a EF8 (if its cable) its quite simple.
Theres a speedo drive that goes into the gearbox. Sits at the top back of the gearbox (common for them to lift up a little bit and then speedo works on and off).
From there there is a cable that goes into the speedo drive then runs into the dash. If there is slack in it then speed will bounce around 10kph. a little bit of bounce is ok.
Its also common for this to pop out at ether end which would stop speedo working.

So if it was me what I would do is.

Remove speedo drive from gear box and check it still has all its teeth left.
Check the inside of the gear on the speedo drive isnt just free spinning with out moving the cable plug.

If that all checks out then I would plug it all back together tight and remove the dash.
With the dash removed jack the car up so both front wheels are off the ground.
Get some one to spin the wheels while you watch the cable for movement. Doesn't matter what gear it is in but having the clutch in helps so your not spinning the engine as well.

If the cable spins fine then plug the dash back in. Make sure the cable clips all the way in.
The speedo is mechanical so its very unlikly anything in the dash would be broken unless some one tried winding it backwards.

Vtec wont work with out proper speed reading. Need to be above 34Kph for it to enable.


Report back once you have done all those or if one has fixed the problem.

Read carefully,

The speed sensor comes in 3 parts. The electronic part, the gear part and the little key that joins the 2. Most VSS failures come from the little key wears out and loses it shape. You must check the condition of this part.

Otherwise the cluster is at fault.

EF8 will be electronic. Thats if it is the same as the EF9.

Quite correct Gudgeon, the speedo is electronic.
After the new part didn't fix the fault, I rescued the old one out of the bin into which I threw it after swapping them over. I'll take that one apart 1st, and get a grasp on things. I did pull it apart in the begining to see if it was something I could fix myslef. BUt I don't rememeber how it looked, as it was quite a while ago.
Hopefully tommorrow will be a snowday too, and I'll perform an autopsy on the old one on the coffee table.
It'll be real good for the Vtec to work again. It's long overdue for a good blow out. (The mrs sure doesn't give it one)

The 2 10mm bolts will separate the VSS.

Bumping this old thread,
We still have no f-king speedo. And it's gotten no easier to work on. Just before I jacked it up, and got the mrs to sit behind the wheel. She let the clutch out in top gear, while I wiggled the plug to see if there is a broken wire anywhere. But the needle didn't so much as flicker.
I pulled the old sensor out of the shed, and pulled it apart again. The square key looked to be in okay condition.
The WOF runs out tommorrow. Since the last inspection, it's done a whopping 17kms. (According to the odometer lol)
Rereading gudeons above post, he'd suggest the cluster may be faulty? How the hell do I even get that out?
Does anyone in Christchurch have known to be good parts I can try to test if they're the problem? Anyone? It's getting to the point where she might just sell it.
I build my own engines, gearboxes, and diffs. But this car is next to impossible to work on. I only have to lift the bonnet and I start tearing my hair out.

Speedo is straight forward to remove:

The shroud covering the speedo can be removed. There are 4 screws holding it in. 2 at the front, underneath and 2 at the back, covered to 2 plastic covers. Undo those, remove the screws carefully and then you will see 4 screws holding the cluster to the dash.

Get the workshop manual for the car here: Honda / Acura Manuals - Hondahookup.com that will tell you how to get the dash out and also how the speed sensing system works. There is a lot of info in these manuals, so it may take you a bit of looking to find the right section, I'd start with the electrics section.

Assuming it's the same as the electronic speedo on my old Accord it uses a 5V square wave to transmit the speed signal. If I were in your place I would probably pull the dash out and put a multimeter across the speedo signal wire (from the dash plug) to a ground, and see if I see any voltage coming through when the wheels turn. Given that it's a waveform, rather than a constant voltage, the multimeter will bounce all over the place if it's working, or give you a flat 0V if it's not. I'd guess that signal is working, in which case the fault is within the dash. In that case I would go look for a new dash at pick a part, OR buy another of these kits: Short Circuits Three Project - Waveform Generator - Jaycar Electronics, which I used before to simulate the VSS, which will allow you to bench test the speedo.

Pity you are in Chch or I would give you a hand.

Thanks Gudgeon.
And especially thanks Cubic. Thats the kind of help I've been seeking. I'll have to read on that link, and try extrapolte from a diagram which pin is the speedometer feed yeah? Man I hope I can fix it. The poor old Vtec hasn't done it's thing for a very long time.

Tech - PR3/PW0 Wiring

B16 = VSS

What is hard about working on an Ef8? Speedo drive sensor is 5 minute job, remove intake pipe and undo 1 10mm bolt and it pulls out of box.

On the more helpful side of things, as gudgen said the drive key wears out in them ensure this is mint before removing ya cluster etc

I guess you could do the multimeter trick at the VSS end first, if that's easier to get to/trace than the dash wiring. If you get a signal there you can rule it out as the cause.

Which wires would I test on the VSS itself Cubic? There's three isn't there? That would be smarter than ripping the dash apart. Although chaning a cluster would be less f-ing about than cursing and swearing under the bonnet.

Startlet, it's hard to work on because the engine is mounted in the car the 90 degrees to how it should be. Simple really. I wont buy a car myself that has the engine round the wrong way.

I had a look at the most relevant manuals on hondahookup and they all said it was a mechanical speedo cable Still, you say yours is electronic so I'll make a few assumptions. The manual where I looked at the dash wiring diagram said the speed wire was yellow/red, which aligns with gudgens link. If there is a yellow/red wire coming out of your speed sensor I would the positive of the multimeter on this and the negative onto any bolt that's screwed into the chassis, making sure that your multimeter is set to measure voltage, not current!

If that doesn't work i would try all three wires coming out of the speed sensor in the same way. If none of them worked I would pull the dash out, sounds like it's actually quite easy.

Bahaha engine round the wrong way? Great attitude

You wont get far working on cars if you can only fix ones with North/South configurations.

My advise would be take it to someone who is prepared to work on a FWD car if its too much of a brain buster for you

Thanks for your help Cubic! Without from people like you, oldschoolers like me would have to pay someone to try fix it.
I'll give that a try next chance I get.

I'm not giving up yet starlet.
But the time will hopefully scome in the next 12 months or so we'll be an all north/south family. (I already have 7 cars like that) I took a couple of beers over to my neighbours tonight. He and his mate were trying to do the cambelt on his honda. They weren't having a nice time of it either.

Give up, Pay a professional. It'll work out cheaper and less stressful in the longrun

How about you stop spamming my thread?
If you're not offering actual advise pertinent to my question, then stop wasting my time and go annoy someone else.