Hey,
I bought a '91 240 DL sedan last fall. The speedometer wasn't working. I replaced the sender on the differential and then the speedometer started working but reads 5mph fast.
My car is gas but the cluster has a diesel glow plug light and when I took out the cluster it's been written on like it's from a salvage yard. I'm also getting a 3-1-1 error, rough idle, not like the smooth idle of my turbo wagon, and sometimes the sedan dies if I slow down really fast after it's been running about 10 minutes. It doesn't die after that.
Could the previous owner have replaced the instrument cluster with the wrong model?

Thanks!!
Greg

 

abs and non-abs cars have different tone rings in the rear end, and yes, different speedometers.

the broken odometer is /usually/ a broken little plastic gear inside.. they CAN usually be home-repaired, severeal people sell that gear. google volvo 240 odometer repair.

there is an output from the speedometer module thats connected to the ECU (Engine Control Unit). that 3-1-1 error is saying that isn't connected, and yes, that can cause idle issues. note, btw, if you go in there.. if your car doesn't have a tachometer, there's a red-white wire THAT SHOULD NOT BE CONNECTED TO ANYTHING. people will plug this in an apparently empty connector on the speedo and fry the speedometer.

I've got the greenbooks for wiring diagrams for all year 240's but not on this computer, I can look up what color that speedo->ECU wire is, and wherei t should be connected.

 

Does your car have ABS? If so, I would try to get a different cluster from another car with ABS. As Pierce said, there is different tone rings which could account for the problem of the speedometer reading too fast.

Regarding the 3-1-1 code, that is due to the ECU not receiving the speed signal coming from the cluster. This is the cause of the engine dying on fast deceleration.

If the previous owner installed a diesel cluster into the car, that may account for the missing signal. Take a look at the instrument cluster circuit board. If you follow the trace from the double spade plug where the yellow wire connects, it should also go to one of pins of the semi-circle plugs. I'm not sure if a diesel cluster has the same signal.

The problem with the odometer not working may be the broken gear or may be due to a fried ITT 2115 chip on the speedometer circuit board. If the 2115 chip is fried, it will also throw the 3-1-1 code.

Getting another cluster seems like the simplest solution to your issues. I picked one from a junkyard about a year ago and it cost me $35. If you go this route, make sure you get one for ABS if your car has ABS. Also, when looking in the JY, check the trip odometer. If it reads 000, most likely the odometer gear is broken. I would try to get one that has a good gear in case yours is broken.

There are several good sites out there regarding DIY speedo repair. Here is a good one that will help you troubleshoot the speedo if you are electronically inclined.

Electronic Speedometer Notes

Good luck

 

Thanks you guys,
I do not have abs. The odometer is working ok. I took the cluster apart this weekend so I could fix the clock. I replaced two capacitors and now the clock seems to be keeping time. I cleaned up the cluster window and now it looks a lot better anyway.
I cleaned and tightened all the connections. My cluster had a little guard for the red/white wire and it is not connected. I can take it apart again and check the yellow wire. Thanks for the link.
I still have the 311 error code but I can't seem to clear code. Maybe I'm crazy but the car seems to be running smoother. Probably because I cleaned everything up so I feel that way.
I turn the key on
I put the code reader connector in hole 2
I push the button for a sec and read the 311 code
That's the only code
I hold the button for 5 seconds after code and let up
The light is supposed to blink then I'm supposed to hold the button for
5 more seconds?
The light never blinks after I hold it 5 seconds after the code.

I think I'm explaining this right.
Thanks again!
Greg

 

To reset the codes, you put the connector into socket 2, turn the key on (II position, engine not running), press and hold the button for 5 seconds. The LED should come on and remain on. Press and hold the button again for 5 seconds. The LED should turn off.

If that doesn't work, simply disconnect the battery for a minute. That should reset the code.

 

I ended up buying a correct cluster from Dave at Wagonmeister. Works beautifully. Thanks you guys!