Yet another speed gauge gremlin topic.

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balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Yet another speed gauge gremlin topic.

Post by balto8 » Wed Jan 06, 2016 11:48 pm

Hi all.

Been through ALL of the speedo threads I could find. Reading them has prepared me to this new problem.

So I start the car and the speedo and odometer are easy and ok. After I drive about 10 kms the needle starts jumping up and down. 50% of the time it displays the right speed, the other half is jumpy. Afer 30 minutes on the road, when I come into city, stopped at red lights, speedo jumps in slightly and odometer keeps counting kms though i'm standing.

Been told first thing to try is remove speedo block and clean connections. Mainly because finding a speed sensor is an impossible thing nowadays.

Lucky our spanish 480 Oracle, Mr. Zárraga, has gone a few times over reparing speedos. SO as long as it's not the speed sensor guess I'll solve this one too. There's this DIY pdf he published in 2011. It's in spanish but with lots of self-explanatory pics.

http://www.odometergears.com/documentat ... panish.pdf

I quote "doingitsideways" saying "this car will NEVER be fixed. Less broken is more like it."
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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brinkie
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Re: Yet another speed gauge gremlin topic.

Post by brinkie » Fri Jan 08, 2016 4:21 pm

The instruction you quote is a mechanical repair of the cogwheel driving the odometer. Usually a faulty speedometer stems from faulty electrical connections, or (very rarely) electronics gone bad.

First you should try and re-solder the pins under the connectors on the main PCB and apply contact cleaner inside the connectors. If the problem persists, there might be another cause.

Assuming you have a later model Volvo 480 (green and grey connector).
There is a little flat cable wit a blue connector, which connects the speedo unit to the main PCB (+12V supply, ground, speedo sensor signal input and speed signal output (for the cruise control and info centre). The insulation is brittle, and will start to crumble if you touch it. If the wires start touching each other, the signal of the speedo will be distorted and thus cause the jumping of the speedometer. If the insulation is bad, try and isolate the wires by putting a piece of insulating tape alternately between the wires, so they won't touch each other.

I think I have repaired over a dozen speedos already, and next weekend I will get two more - It's becoming a routine job :rofl:
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

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Yet another speed gauge gremlin topic.

Post by balto8 » Fri Jan 08, 2016 6:35 pm

Thank you Brinkie for your answer. Every thought is welcome.

Yes, that repair guide on the link I've sent is for the broken tooth on the cogwheel. Also a common failure if you reset the partial odometer when the car is running as you force the mechanism counterclockwise when it's turning clockwise (that's what I've been explained). Also been told that a missing tooth on the cogwheel will make the needle jumpy. But I guess there colud be various causes (as allways in our beloved 480s)

I've been also told to clean and spray all connections on the back of the tachometer. Specially theese connnections you've metioned.

Today I took a trip to this scrapyard close to my town and even on highway at 120 kms/h the needle has bevaved without issues all the way. So why is it intermitent? My guess is also some bad connection. Been told first thing to do would be cleanig and assuring theese two pins. I'll let you know my advances.

Does anyone know how to get my hands on a speed sensor? Not that I think it will be the cause, but looking to have a spare as they're getting scarce. Mine would be ref. 3413744

Image

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1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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Baxter
Started learning about 480
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Joined: Thu Nov 12, 2015 7:44 pm
Location: Paris

Re: Yet another speed gauge gremlin topic.

Post by Baxter » Tue Jan 12, 2016 5:52 pm

I repaired my odometer this weekend and I notice there are a lot of soldering connects on it.

http://www.volvo-480-europe.org/forum/v ... 8&start=40

Some of them could have dry soldering causing intermittent problems.

https://www.google.es/search?client=ope ... 8&oe=UTF-8

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Yet another speed gauge gremlin topic.

Post by balto8 » Wed Jan 13, 2016 10:12 pm

Fire! Fire!

I took out the speedo and disassembled the thing. Cleaned all the circuits thoroughly with CRC cleaner, let it dry for half an hour and then reassemble.

Once I connected the green and grey connector on the back of the board, after two minutes, some weird smell started to come out followed by this white smoke. I quickly pulled both connectors. Then tried angain next morning and got again the smell and the smoke coming from the infocenter board.

So I guess my infocenter board is dead now. Maybe something else? The motherboard seems fine I can't see no burnt or damaged solderings.

Anyone with a spare infocenter board for my model?

Damm car !!!! :angry:

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1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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brinkie
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Re: Yet another speed gauge gremlin topic.

Post by brinkie » Thu Jan 14, 2016 7:21 am

Are you sure it is the info centre board, and not some residue of the cleaning agent? The backlights generate quite a lot of heat. Is the info centre working? Is the smell and smoke also coming if you fit the unit to the car without the info centre?

Further thoughts: if the magic smoke is indeed coming from the info centre, you should see some fried components. The board on the picture looks actually very healthy.
I do have a spare working info centre computer from a MY 1991 480 Turbo, but it is my last spare "VDO 734" or "H" board (the others I have are all pre-1991 model year, assuming 48 litre tank capacity instead of 60), so I am quite reluctant to sell.
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

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Yet another speed gauge gremlin topic.

Post by balto8 » Thu Jan 14, 2016 2:41 pm

Yes. I also thought that it could be the residue of the CRC causing the smell and smoke, but forgot to mention that the infocenter board got quite hot. I could sense the heat coming from the multipin blue connection to the main board area. So I figured that a short-circuit had happened over there.

I've also substituted every bulb on the board for LEDs but the infocenter halogen one. Anyway, ignition was off and no key on lock. Guess I should have pulled the battery aswell...

I have not tried though to connect the infocenter and give it a try as I don't feel comfortable with the smoke and the heat. I don't want to end up with the car in flames.

Lucky the ALLMIGTHY Mr. Zárraga has already sent me a a revised complete instrument set. So I'll be trying again this weekend. Thank you Robert anyway for the offering.

To be followed.
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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Baxter
Started learning about 480
Posts: 92
Joined: Thu Nov 12, 2015 7:44 pm
Location: Paris

Re: Yet another speed gauge gremlin topic.

Post by Baxter » Thu Jan 14, 2016 8:30 pm

The smell could come from the halogen bulbs, they heat a lot. Too much in my opinion for a cluster.

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Yet another speed gauge gremlin topic.

Post by balto8 » Sun Feb 14, 2016 10:03 pm

After I fried the infocenter board when trying to clean the connections on the back of the main board I had to replace the whole thing.

Also due to so many dashboard disassemble and reassemble the plastic was falling apart. I had to reinforce almost everywhere with pounds of poxiline. Now its all firm and steady.

So today I finally had the time to replace the gearbox speed sensor for a scrappy one in quite good condition. As I managed to take out the sensor ( narrow, nasty job) I understood that had been the problem from the first moment. It came all damaged, rotten. I'm getting used to try and screw up some part of the car first, and then I finally nail the problem. I don't think I have solved any problem on my car this far on the first atempt.

So I have uploaded this couple of videos of my speed gauge behaviour before and after the speed sensor replacement, so anyone with the same problem will recognize it and spare himself the calvary I just went though ( again).

Before

https://youtu.be/Kn8Jswr4dFk

After

https://youtu.be/OYUGrqw9lhw

This car is like this girlfriend I had in college. Probably the cutest thing I have ever put my hands on and a complete nightmare of a girl. Lucky I found soon enough she was doing " a few more guys" at the same time. :wall:
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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brinkie
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Posts: 605
Joined: Mon Apr 21, 2014 11:20 am
Location: The Netherlands
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Re: Yet another speed gauge gremlin topic.

Post by brinkie » Tue Feb 16, 2016 6:11 pm

A Volvo 480...

They don't just have gremlins...

They come standard with a Zombie Apocalypse! :crazy:

Image

(sorry couldn't help posting this :P )
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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