Speedo Problems, the cure!
Discussion
OK all, I know what the problem is.
The sensor does NOT fail. It is just a piece of magnetised metal, it can not fail.
If you follow the wire from the sensor you will see that it enters the cabin via the front nearside bulk head. On entering it looks like the whole is sealed, it is, but it is not water tight.
If you drive in wet conditions water WILL get in. The problem is that this does not cause the problem immediately, it is the after affects, i.e. corrosion of the connector inside the cabin.
Look inside the panel, shine a torch onto the wire and you will see where the water has trickled down into the connector, it won't be much, but it is enough.
I took mine to Unicar in Leeds when mine went again and the guys were thorough, they found the problem. I had a new sensor but to prove the point, we bypassed the connector, the wires were completely corroded. We stripped the wire back to good wire and then simply connected using bullet connectors. Hey presto, all is now working.
We also think that the water does not necessarily come from water thrown up from the front wheel, we think it may be surplus water from the windscreen draining off the side of the windscreen and down the bulk head. I now have a piece of rubber all along the bottom of the windscreen that directs surplus water away.
You can prove all of this by doing exactly what I have done. Remove the connector and bypass it.
So, if your have a speedo that jumps around, this IS the problem. If your speedo stops working, this IS the problem. The reason it is intermittent is that the connector has either dried off or the vibration is causing an on off effect, a bit like a switch on the corroded wires.
One last thing, if you do not catch it in time, you will blow the electrics in the speedo itself and a new one will be required. When you replace this speedo with another, it will not work, till you do the above.
After you affect all the above, get some silicon sealer and seal the whole from the inside and outside if you can.
Hope this all makes sense.
Ash.
The sensor does NOT fail. It is just a piece of magnetised metal, it can not fail.
If you follow the wire from the sensor you will see that it enters the cabin via the front nearside bulk head. On entering it looks like the whole is sealed, it is, but it is not water tight.
If you drive in wet conditions water WILL get in. The problem is that this does not cause the problem immediately, it is the after affects, i.e. corrosion of the connector inside the cabin.
Look inside the panel, shine a torch onto the wire and you will see where the water has trickled down into the connector, it won't be much, but it is enough.
I took mine to Unicar in Leeds when mine went again and the guys were thorough, they found the problem. I had a new sensor but to prove the point, we bypassed the connector, the wires were completely corroded. We stripped the wire back to good wire and then simply connected using bullet connectors. Hey presto, all is now working.
We also think that the water does not necessarily come from water thrown up from the front wheel, we think it may be surplus water from the windscreen draining off the side of the windscreen and down the bulk head. I now have a piece of rubber all along the bottom of the windscreen that directs surplus water away.
You can prove all of this by doing exactly what I have done. Remove the connector and bypass it.
So, if your have a speedo that jumps around, this IS the problem. If your speedo stops working, this IS the problem. The reason it is intermittent is that the connector has either dried off or the vibration is causing an on off effect, a bit like a switch on the corroded wires.
One last thing, if you do not catch it in time, you will blow the electrics in the speedo itself and a new one will be required. When you replace this speedo with another, it will not work, till you do the above.
After you affect all the above, get some silicon sealer and seal the whole from the inside and outside if you can.
Hope this all makes sense.
Ash.
I have posted this before, but it looks like it may need repeating. There is another source of moisture that causes the speedo to malfunction when the moisture gets in the connector:
Dear all:
This is something that you may also want to check when your speedometer acts up. It may just save you the expense of replacing the speedometer or the wheel sensor needlessly. Condensation from the a/c expansion valve can drip onto the speedometer connector that sits below it in the footwell. This has happened to me twice now on very humid days. Mine has fixed itself each time just by drying out over the next couple of days, but the real fix for this is detailed below:
From the 2006 US Assembly Manual, pages 48-50:
18. Intermitted Erratic, or Inoperative speedometer It has come to our attention that under certain conditions moisture can build up in the speedometer sensor plug under the dash, if this should occur, erratic or no speedometer operation can result. Under humid driving conditions, exiting and entering the vehicle can cause the A/C expansion valve and evaporator lines to sweat heavily. This condensation can drip onto electric components under the A/C unit. If this moisture enters the speedometer sensor plug, it can fowl up or even block the signal all together. To correct this problem A/C insulation tape can be used to seal the expansion valve from the humid air. To check for this condition, remove the fuse/relay access panel in the passenger side foot well. Check for a wet carpet directly under the expansion valve on the left side of the A/C box. Separate the speedometer plug and check for moisture inside the plug.
Any of these conditions indicates the likelihood of condensation dripping from the expansion valve above. Note: This should be check when these symptoms are occurring. If the car sits any length of time these area can dry out and the problem may go away.
To eliminate this condition the expansion valve and exposed metal lines off of the HVAC box must be covered with a special tar like material referred to as A/C insulation tape.
Left photo is of the label for the Four Seasons brand sold at most auto parts stores. To install, remove the lower dash cover under the radio for easy access to the components. The expansion valve must be dry and close to room temperature for the tape to stick properly. Cut three 9” long strips from the tape.
Start at the box and wrap the tape around the valve and line. Push it up tight against the box. Wrap the two other strips around the components, slightly overlapping each. Mold the tape tightly around the components.
When finished all of the metal parts of the A/C expansion valve and pressure lines should be covered and sealed off. Start the engine and run the A/C. Check for any dripping around the tape. If this occurs, look for an exposed area. The speedometer operation should return to normal once the plug is dried out. With the plug apart use a hair dryer or shop air to dry out the plug connection.
Hope that helps.
Craig
Dear all:
This is something that you may also want to check when your speedometer acts up. It may just save you the expense of replacing the speedometer or the wheel sensor needlessly. Condensation from the a/c expansion valve can drip onto the speedometer connector that sits below it in the footwell. This has happened to me twice now on very humid days. Mine has fixed itself each time just by drying out over the next couple of days, but the real fix for this is detailed below:
From the 2006 US Assembly Manual, pages 48-50:
18. Intermitted Erratic, or Inoperative speedometer It has come to our attention that under certain conditions moisture can build up in the speedometer sensor plug under the dash, if this should occur, erratic or no speedometer operation can result. Under humid driving conditions, exiting and entering the vehicle can cause the A/C expansion valve and evaporator lines to sweat heavily. This condensation can drip onto electric components under the A/C unit. If this moisture enters the speedometer sensor plug, it can fowl up or even block the signal all together. To correct this problem A/C insulation tape can be used to seal the expansion valve from the humid air. To check for this condition, remove the fuse/relay access panel in the passenger side foot well. Check for a wet carpet directly under the expansion valve on the left side of the A/C box. Separate the speedometer plug and check for moisture inside the plug.
Any of these conditions indicates the likelihood of condensation dripping from the expansion valve above. Note: This should be check when these symptoms are occurring. If the car sits any length of time these area can dry out and the problem may go away.
To eliminate this condition the expansion valve and exposed metal lines off of the HVAC box must be covered with a special tar like material referred to as A/C insulation tape.
Left photo is of the label for the Four Seasons brand sold at most auto parts stores. To install, remove the lower dash cover under the radio for easy access to the components. The expansion valve must be dry and close to room temperature for the tape to stick properly. Cut three 9” long strips from the tape.
Start at the box and wrap the tape around the valve and line. Push it up tight against the box. Wrap the two other strips around the components, slightly overlapping each. Mold the tape tightly around the components.
When finished all of the metal parts of the A/C expansion valve and pressure lines should be covered and sealed off. Start the engine and run the A/C. Check for any dripping around the tape. If this occurs, look for an exposed area. The speedometer operation should return to normal once the plug is dried out. With the plug apart use a hair dryer or shop air to dry out the plug connection.
Hope that helps.
Craig
You can also solve this by tie cabling up the connector so it has a "drip curve" in it. Make it so that the cable coming in goes down, and then heads back up before it reaches teh connector. That way any water following the cable down will harmlessly drip off the bottom of the curve.
If you look at every phone line or satellite cable that enters a house you'll see a similar drip curve.
J
If you look at every phone line or satellite cable that enters a house you'll see a similar drip curve.
J
JimNoble said:
Hmm, shouldn't that speedo plug have some sealing grommets on the wires where they go into the back of the connector?
Jim
Jim
You would think so, but it doesn't. You could also seal the plug wires with some clear silicone as further protection, but the real culprit is the a/c expansion valve and piping, especially on warm/humid days when there is more than normal condensation forming and dripping onto things below. 1gRacing's recommended solution of taping off the piping with the special a/c sealant tape is probably the best solution, but I still think sealing the connectors with some silicone where the wires go in is a good idea too.
Craig
robp said:
Any idea where you can get this A/c insulating tape (in UK)?
A couple of quick searches turned up these possibilities:
http://cgi.ebay.co.uk/Maxflex-insulat
www.maxflex.co.uk/
Edited by caccobra on Thursday 26th October 18:28
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