Chinese Speed sensor, any advice?

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Alan 480
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Re: Chinese Speed sensor, any advice?

Post by Alan 480 » Fri Apr 08, 2016 7:13 pm

if you look at the face of the speedometer it has a 5 digit number, (10753, for a two litre 1993) this is the pulses per mile (in the UK) I assume similar if in km?

I seem to recall/reckon that there are twelve teeth on the shaft that runs next to the speed sensor as when do the rolling radius time Pi etc and do all the arith, I got an answer of 11.89 or similar so as you cant have a part of a tooth it had to be twelve?
Alan

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Re: Chinese Speed sensor, any advice?

Post by brinkie » Sun Apr 10, 2016 9:16 am

Gmac34 wrote:Hello, it's been a while, but I finally got time to do the experiment.
First I tried to use my iPad as a signal generator hooked directly to the sensor socket and the needle moved (I used an headphone amplifier in order to have more voltage, I don't know if the iPad alone would have been sufficient).
So confident that the problem was probably a bad sensor I tried to hook up the Chinese sensor and it worked straight away.
Whe had to machine an adaptor that screws on the Chinese sensor in order to properly mount it and seal the original hole.
I'll have to do a proper test on the road and check if the speed is precise, now I can't since there are no front seats :)
Otherwise, could you write me a couple of gear number/ rpm/ speed combinations so I can check it without leaving the shop, I'm rellay curious.
:hopping:

Might be a great solution because the original Volvo sensors are impossible to find new. I am very curious to the exact sizes of the adaptor.

Anyway, you should get exactly the same speed counts as before. The counting takes places because the coil is interfering with the toothing of the gearbox, and that hasn't changed. So no need to find out gear ratios, unless you have changed the gearbox as well.
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Wed Apr 13, 2016 9:32 am

Hi, yesterday i was able to do a short test drive (around 30km) and I'm pleased to report that the speedometer is working fabulously.

It gives a consistent reading, always about 5km/h more than the gps on my iPhone but this is normal.

The information center reads the speed and seems to work fine.
the only think thai is not working is the odometer, bot the total and partial km do not move.
I suspect it is a different issue (BTW any advice is appreciated :D ).

I have to ask my mechanic for the exact measurements.
I think he could make more at a reasonable price if anyone needs it, it would probably be cheaper than make one yourself as the bit to make the internal threading was rather expensive (it costed me more than the sensor itself), i have to ask him though.

Cheers
Giovanni

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brinkie
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Re: Chinese Speed sensor, any advice?

Post by brinkie » Wed Apr 13, 2016 10:23 am

Alan 480 wrote:if you look at the face of the speedometer it has a 5 digit number, (10753, for a two litre 1993) this is the pulses per mile (in the UK) I assume similar if in km?
In km there are two flavors, K6818 and K6683. K stands for number of pulses per kilometre. In miles there are also two flavors, but I don't know the numbers since I live in the metric part of the world. ;) (edit: K10970 and K10753)

There are basically three types of speedometer, if you don't take the different front into account (MY 1994 came with a new font, earlier cars equipped with catalytic converter came with UNLEADED FUEL ONLY message)

- CH -540797 (km) -540974 (miles); K6818 (K10970 in miles); earliest model, connector with four large pins which mate to four separate metal connectors on the main board. This is a very error-prone connection, some repairmen fix these four pins by soldering them into the connectors, making future repairs to the odometer very difficult, if not impossible! Never EVER resort to this kind of measure... Main board has yellow and blue (CH -519639) or red and yellow connector (CH 519640-540798/540974)
- CH 540798-563100 (km) 540976-563100 (miles); K6818; MY 1989 starts at 536101, MY 1990 starts at 549101 so this change probably happened late 1988 during MY 1989 production. Instead of four metal pins, a small 5-pin connector with a ribbon cable is used, which gives a much more reliable connection. Main board has gray and green connector.
- CH 563101-586299 (km and miles); change to K6683 (K10753 in miles) from MY 1991 onwards.
- CH 586300- (km and miles); front plate change to Volvo Broad font from MY 1994 onwards.
Last edited by brinkie on Mon Apr 03, 2017 8:01 pm, edited 1 time in total.
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

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Re: Chinese Speed sensor, any advice?

Post by brinkie » Wed Apr 13, 2016 2:53 pm

Gmac34 wrote:The information center reads the speed and seems to work fine.
the only think thai is not working is the odometer, bot the total and partial km do not move.
I suspect it is a different issue (BTW any advice is appreciated :D ).
You need to replace the little plastic cog wheel which sits behind the stepper motor on the speedo unit. Available on eBay: http://www.ebay.de/itm/271645832525

I will be very happy if your mechanical man will share the thread sizes with us :D
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

teko996
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Re: Chinese Speed sensor, any advice?

Post by teko996 » Mon May 02, 2016 4:38 pm

I JUST DOUBLE CHECK IF THIS SENSOR CAN BE USED IN MY 2.0 ES 1993. THAT'S OK?
from eBay: MSP6729 ROTATE SPEED SENSOR MAGNETIC 1PC NEW GENERATOR PARTS PICK UP 88uu

P.S.: I'M TRYING TO FIND THIS PART FOR A YEAR.

MANY THANKS

teko996

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Mon May 02, 2016 5:00 pm

Hi, my volvo is a little older (89) but it should be ok.
Unfortunately I do not have the measurements for the adaptor, but if you still have your original sensor you can easily measure the dimensions directly.
The inside of the adapter should be machined to screw on the sensor, that has a 3/8-24UNF thread on it, the outside should have the outer dimension of the middle section, about 12mm if I remember correctly and should be machined to accomodate an O-ring, just like the original sensors does.

the sensor should be mounted very close to the gear, screw the speed sensor in until it touches a gear tooth, then back it out 3/4 of a turn and secure it.

in order to secure it I used the original aluminium bracket and some spacers.

If you need more info I'm here.

P.S. I haven't had the chance to do extensive testing, only a 30km drive between my mechanic and the paint shop, so I'm not sure about the long term reliability.

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Re: Chinese Speed sensor, any advice?

Post by teko996 » Tue May 03, 2016 6:41 pm

THANKS ANYWAY...I'LL TRY BUT MY ONE IS AUTOMATIC.
I HAVE THE OLD ONE.....LET'S TRY!!!!
THANKS

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Re: Chinese Speed sensor, any advice?

Post by brinkie » Tue May 03, 2016 7:19 pm

PLEASE STOP SHOUTING WE ARE NOT DEAF! :roll:
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Tue Jul 05, 2016 8:21 pm

Hello,
I finally got to do some serious testing, using the car for short and long trips, today I did more than 300km.
Unfortunately the speedometer is not performing very well, once the car is hot, let say about after 30km, it start behaving erratically: when the car is speeding up from 45km/h the displayed speed jumps right at 80 /100 km/h and then goes down again only once the car reaches 70km/h

So it is quite precise between 0 - 45km/h and over 75km/h, but terrible in between, like when you are trying to do less than 50km\h and it displays 100km/h.

I haven't found anyone reporting a similar behavior, so I assume it's an issue related to the new speedometer, I would like to understand why it perform differently when the car is cold, it might be related to the temperature of the ghearbox that is messing up the sensor.
Maybe once the sensor is hot the output voltage is higher.
I'm thinking about removing the capacitor in the oscillator, it is theoretically not needed anymore and could be interacting with the signal generated by the sensor.
Unfortunately I'm not a technician, I can solder/dessolder and use an oscilloscope, if anyone has any other idea.......

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Re: Chinese Speed sensor, any advice?

Post by brinkie » Wed Jul 06, 2016 6:23 am

Does the needle jump in the same manner as the trip counter counts? If so, then the instrument panel has a power supply problem.
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Wed Jul 06, 2016 6:43 am

brinkie wrote:Does the needle jump in the same manner as the trip counter counts? If so, then the instrument panel has a power supply problem.
The average speed reflects the displayed speed, more or less, and I also get outstanding fuel economy when doing 50km/h as the computer thinks I'm doing two time the speed, is this what you mean?
Thanks for your help Robert

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Wed Jul 06, 2016 7:04 am

Gmac34 wrote:
brinkie wrote:Does the needle jump in the same manner as the trip counter counts? If so, then the instrument panel has a power supply problem.
The average speed reflects the displayed speed, more or less, and I also get outstanding fuel economy when doing 50km/h as the computer thinks I'm doing two time the speed, is this what you mean?
Thanks for your help Robert
Or probably you meant the odometer, I think so, it is going as fast as the displayed speed, I'll test it today vs the gps odometer on my phone.

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Re: Chinese Speed sensor, any advice?

Post by brinkie » Wed Jul 06, 2016 1:52 pm

No, I meant a wobbly meter and the wobbling coincides with the movement of the trip counter. I found out in my lab that using an inadequate power supply causes a jumping needle.

But how you describe it might as well be a high frequency interference problem with other parts of the engine. Did you take care to use shielded cable and proper grounding/earthing of the signal cable shielding?
Also, is the sensor still in place?
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Thu Jul 07, 2016 11:40 am

No, I don't believe that the wobbling is in sync with the trip meter movement, I'll try to shoot a video.
Still the odometer advances accordingly to the displayed speed,
On a 50km trip (measured by the gps) the odometer sowed 62km
But I wasn't doing 50km/h all the time, I think it would had been even more if I did.

The strange thing is that every morning it works fine for 50/80 km, what could change?

About the the new sensor, it did come wit a shielded cable, but we did not know where to connect the shield as the original cable doesn't seem to be shielded, so we just cat it to length and soldered on the connector from the old sensor.

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Thu Jul 07, 2016 3:39 pm

brinkie wrote:No, I meant a wobbly meter and the wobbling coincides with the movement of the trip counter. I found out in my lab that using an inadequate power supply causes a jumping needle.

But how you describe it might as well be a high frequency interference problem with other parts of the engine. Did you take care to use shielded cable and proper grounding/earthing of the signal cable shielding?
Also, is the sensor still in place?
I took a look under the bonnet, I don't think I can check on the correct mounting of the sensor without going to the mechanic, I have a turbo, so it is hidden, what I do see is that the sensor cable is unnecessary long so I can trim it further, and I can also try to ground it.

But where?
I see that while the connector on the sensor side has only 2 pins in it the connector on the other side has 3, is the spare pin the ground? Otherwise where would be a good spot?

If trimming and grounding are not enough, I think I could run a cable from the connector under the bonnet and test the signal with my portable oscilloscope wile driving to see what is going on.

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Re: Chinese Speed sensor, any advice?

Post by glasgowjim » Fri Jul 08, 2016 4:34 pm

Gmac have found a speedo sensor for a 480 at the bottom of my shed :D

You have a pm :D

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Re: Chinese Speed sensor, any advice?

Post by Gmac34 » Sun Jul 10, 2016 10:21 am

I think I finally got to the end of this.

I used my portable oscilloscope to see what was going on while driving, with cables running back and fort from the bonnet :)

Anyhow, the sensor works fine, apparently it doesn't pick up interference and the signal is clean, it is not a perfect sinusoidal though.

The same applies to the instrument cluster, tested using the signal generator it works fine even while driving.

To keep it short, I finally got some good results amplifying the signal from the sensor,
it is odd, as using the signal generator, varying the voltage, the instrument either reads the speed perfectly or doesn’t read at all, so I wasn’t able to replicate the same behaviour I get on the road with the signal generator, still, probably it is a consequence of the irregular wave shape.

After testing with a small headphone amplifier I tried also to use a step up transformer.

The amplifier gives perfect results, as well as the transformer which is a much simpler solution as it doesn’t need power.
There is a catch: every transformer will have a different bandwidth, the one I used is nothing special: a 250v/12v 3VA unit (the sensor is connected on the 12v side, the instrument on the 250v)

but, since the sensor outputs a variable frequency from 0hz at 0 km/h to 277hz at 120km/h and every transformer is less efficient as frequency goes down, there is some twitching in the reading below 30km/h (the needle wobbles a little, but much less than before, only +-3km/h)

A bigger transformer would probably perform better on low frequency and the amplifier would be even more linear but it si quite complex to get a dual power supply from the 12v in a car without messing with the groud.

I should check if my mechanic mounted the sensor as near as possible to the toothed gear, the voltage generated by the sensor is dependent on that gap and an incorrect mounting would explain the low voltage I get from the sensor.

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