Smoke in the speedo

[gutma]

The other day I changed my speedo because the cogwheels were broken and when taking a ride to test it, smoke came out of the back of the speedometer and the green circuit of it burned just above where the cogwheels sits, and I thinks also the blue connector smokes and because of that I had to change a fuse of the box since the instrument cluster did not work. The problem is, I changed the instrument cluster for a new one and it works everything but not the speedometer or parcial km count and the cig wheels are ok do not know what it can be, also the info center shows everything but not the consumption or average speed.

[brinkie]

The other day I changed my speedo because the cogwheels were broken and when taking a ride to test it, smoke came out of the back of the speedometer and the green circuit of it burned just above where the cogwheels sits, and I thinks also the blue connector smokes and because of that I had to change a fuse of the box since the instrument cluster did not work. The problem is, I changed the instrument cluster for a new one and it works everything but not the speedometer or parcial km count and the cig wheels are ok do not know what it can be, also the info center shows everything but not the consumption or average speed.

Happened to me once, I will tell you what might have been wrong.

The little blue connector that connects the main board to the speedometer has a piece of flat cable attached to it. The flat cable carries, amongst speedometer signals, +12V from the battery and ground (chassis earth).
However, the insulation of the flat cable ages very badly and crumbles away. Without proper insulation, the +12V and/or ground wires might come into contact with the infocentre computer board which sits right on top of this cable.

So if the "magic smoke" comes out of your instrument cluster and the cable insulation has come off, either the infocentre or the speedometer electronics might have died. Once you have sorted out the insulation (just wrap a piece of tape in between the cables and stick a piece on top to make sure there is no contact), you can safely swap the infocentre computer and see if everything works properly now.

No info of fuel consumption or average speed might be caused by faulty speedometer electronics. This is not very easy to swap, you have to take the speedometer apart.

[gutma]

I taped the wires of the blue cable, and test the other speedo that I have after the smoke but no speedo neither. The info center seems ok but no consumption or speed average. How can I know if the new speedo is ok? Because it's looks ok, not with a burned circuit like the one that was the day of the smoke, but the new one don't do anything.

[gutma]

Today I have re-soldered all the connections of the board for the green and gray connectors, I have also re-soldered the connections to the board of the small blue connector and the blue connector on the speedometer, I have connected it, and the speedometer still does not work and the infocenter continues with three stripes in consumption and average speed. How can I check that the speedometer electronics works? Could the speed sensor have been damaged by the magic smoke that caused the other speedometer to break down and the fuses blown?

[gutma]

Today also put another instrument cluster and no speedo and three lines in the infocenter also..

[brinkie]

Electrical power to the speedometer us the same as the rev counter, so my next question is: does the rev counter work? If not, the problem is in the power supply.

You can also measure the resistance of the speedometer sensor in the gearbox. Pin 6 (signal) and 12 (ground) of the grey connector lead to the sensor. The resistance should be low, like 3 ohms.

Finally: is the earth cable on top of the engine still connected properly? Many times the lug breaks off, or makes poor contact. This causes many electronics to fail.

[balto8]

Gutma.

Maybe you don't want to give up, this soon with your infocenter, but I have gone exactly through the same history with mine (including smoke coming from the infocenter board) and the wisest thing to do, which will save you money and time, is to send the speedo to Robert and let him take a look.

It might seem expensive : send it to Holland, have it repaired and then sent back. But in the end end it is worth every euro and saves you from what I have most hated of having to deal with while bringing my ruinous car back to life : time consumption.

By the way. About time you post some pictures of your gorgeous Two-Tone Turbo, which I had my eye on for a while.

[gutma]

Tomorrow I am going to measure the speed sensor, because I have rev counter working, only the speedo is not working. Where is the earth cable in the top of the motor? . If is not the speed sensor, I am going to send you my speedo Brinkie. Thanks for the answers.

[Alan 480]

Tomorrow I am going to measure the speed sensor, because I have rev counter working, only the speedo is not working. Where is the earth cable in the top of the motor? . If is not the speed sensor, I am going to send you my speedo Brinkie. Thanks for the answers.

runs from top of engine at 'front' end (timing belt) at back of engine across to the loom, they suffer as I don't think it is a braided cable so fails at the crimp, just above the injectors

not sure where if a turbo???