Hello all. My first post.

Have been attempting to rescue a 1987 245DL which sat in a garage for over 18 years. Below is the car.

Making headway through changing fuel tank, pumps, battery, filters, etc., I finally got her started but then I found the speedo and odometer do not function. I found a burnt area on the board in the back of the speedo, where a resistor and diode might be toasted. I think that is likely the cause for the faulty speedo. Can anyone please help me identify the resistors and diode? Many thanks in advance.

 

see if there's something on Dave's Volvo page

https://www.240turbo.com/240gaugewir...trumentcluster

or

https://www.davebarton.com/pdf/240od...r-electric.pdf

 

Thanks a bunch for the tip. I did read Dave Barton's pages earlier. There's one photo showing the burnt resistor, but I can't really make out the colors on the resistor to determine what to buy.

Wonder if anyone with a 87 Cluster might have a photo of the resistor. I'm hoping some members might have that photo handy.

 

Contact POWL'S speedometer and auto center. They should be able to get you what you need. They are in Lancaster PA.

 

Try this site:

Electronic Speedometer Notes

There is a pic of the resistor referenced but the image is too blurry to read the color codes. However, if you scroll down Art has a hand-drawn schematic. If you are good at reading a schematic you should be able to get the value from it. For the diode it looks like the numbers are still readable if you remove it.

Unfortunately you really need to figure out why the items got burned as replacing the components might result in the same failure. Also there may be other components - like the ITT chip - that also may be damaged.

 

thank you so much for your help. You make an excellent point to first figure out the cause.

Btw, what and where is the ITT chip? is that within the speedo and/or cluster?

 

In your top picture it is the chip in the lower part of the image. You can see the ITT label on it.

Many times people that don't have a tachometer remove their instrument cluster and don't mark the connections. When they go to re-install it they find a loose red/white wire in the dash and try to find a home for it. They tend to connect it to the double spade connector on the back of the cluster and it fries the cluster when you start the engine. Many times it fries the ITT chip. That may be what happened to yours, I can't be sure. The site I linked to has multiple threads on the instrument cluster as well as other useful information on repairing your 240.

 

Thanks again for responding. I am not sure what caused the damage when I found the speedo dead-on-arrival. I do note the red/white tach wire which I left alone.

Will likely get a replacement cluster and will update.

 

Update: I found a 18-gauge wire from the alternator may have shorted. That wire I believe is the Charging Indicator to the Instrument Cluster. I suspect that could have fried the resistor. I am not sure.

I use heat shrink wrapping as much as I could to insulate the Charging Indicator wire as well as an an adjacent wire (Oil Pressure Sensor) to protect them and correct the short.

I am hoping that was the culprit before I install a new Cluster.

I am not proficient at reading schematics so I cannot get the value of the resistor in question. Also, i am not sure what else was damaged so i think a new cluster is the way to go.