1985 240 DL bought it without gas gauge working. Replaced sending unit with known working unit from a 92 240 and still gauge not working. I removed the cluster and found the voltage regulator but it looked different than the voltage regulator on my 92 cluster I pulled. There are many differences from the 85 and 92 cluster so it hasn't been much help. The temp gauge is working just fine and the previous owner broke the locking mechanism on the speedo cable so the speedometer is jumpy. What could it mean that the gas gauge is not working but the rest is? I also replaced the gauge itself from my 92 and still nothing. I am going to use the test light soon to check the gauge wire coming from sending unit and on the back of the cluster. Is there any way to test the gauge itself?

Lastly,

I can post pics of rear of cluster soon but what connections are what? All I have on the back of my cluster is the one yellow/red female connector and the full circle and half circle connections which I believe are just for the lights on the cluster. So what does this one yellow/red wire power?

Thanks.

 

It is well documented online that the aftermarket sending units come wired incorrectly. When I installed one, the black connector had the wires switched in it and corrected it prior to installation. If you installed an aftermarket unit, I would go back and re-check the wiring. It is all written up here:

In the Tank - 240 Volvo Tank Pump and Sender

 

Both are original. The 85 is original and the 92 is original I pulled it from my parts 240 in the yard. I found out the yellow/red wire powers the overdrive indicator light. I guess the power for the gauges and what not is on the electronic board itself sandwiched in the cluster. Is there any way to test a gauge by itself?

I guess no one has had experience with this. I am not having sending unit issues. As I said I already replaced my sending unit with a working one from my 92 and made sure all connections are good. At times while I have had the car the gauge has jumped here or there so I am thinking it is electrical from the cluster area. I am thinking it may be the voltage regulator. Again everything worked but fuel gauge and I believe this regulator powers both temp and gas apparently so I am unsure how one gauge works while the other doesn't.

 

I would check the wiring in the rear of the car. In the link I posted, refer to the sender diagnostic section to test the signal from the sending unit. Once verified there, trace the wiring to the cluster and perform the same test there.

I doubt the gauge is having issues as I have not heard of any failures there. I have had issues on my cluster with bad connections on the circle and half-circle connectors. I cleaned them up good and have had issues since.

 

So I checked connections at the cluster and all was good. I did notice that the light only went off for one of the half circle and circle connections. Is that how its suppose to be or should every wire be giving off power? I am also going to check my gray gauge wire in the trunk but I have been doing a lot of fuel work back there and the wiring looks clean and together. I am going to check those wires in the trunk but how did you clean those connections. Just a small pencil file or something?

Thanks

 

To clean all the pins on the back of the instrument cluster I used a scotchbrite pad and rubbing alcohol. Someone had years ago gone nuts with the dielectric grease and it was all crusty. The rubbing alcohol cleaned that up. I used some sort of electrical contact cleaner on the connector.

 

Ok so basically I am getting nothing on my test light for the gray and yellow/red wires in the connector going to the sending unit. For voltage I am getting 0 for the yellow/red wire and like -.10 for the gray wire. I am getting 12 volts across the board on all fuses in the fusebox. In the wiring diagrams the power arrows went from the gauge to the sending unit, not the other way around. So I am thinking maybe plugging in my cluster would help but it didn't. Actually now removing my cluster none of my gauges work. I had a feeling that might happen. I hope I didn't over tighten anything potentially cracking that board or something similar.

Any thoughts? Can anyone else chime in on this?

 

Yes, you need to have the instrument cluster plugged in to get 10v on the gray wire to the sending unit. According to my Haynes manual, the 10v comes off of the voltage regulator on the instrument cluster. When you plug in your cluster and turn the key to the II position, are the idiot lights coming on in the cluster? If so, that basically ensures that you have 12v to the cluster. If they don't come on then your cluster is not getting proper power. If the cluster has proper power, check the voltage regulator. It has three pins - one should be 12v, the middle pin should be ground and the third pin should be producing 10v.

 

I will have to get back to you on those numbers. Schools back in

Anyway, from my research it looks like on the other side of the electronic board that some sort of relay looking thing is suppose to plug into some spade connectors attached to the voltage regulator? Would this be the replacement necessary or will the actual voltage regulator with the 3 pins be the replacement?

Thanks

 

You really can't say what to replace until the measurements are made. If you have no 12v to the regulator (the three pin transistor looking thing) then it isn't the culprit. If there is 12v to the regulator but no 10v coming out, then the regulator is bad.

 

Act,

OK, so I have voltage on all necessary pins. My readings were 12.28, 9.91, and 0.05 on the ground. Any thoughts?

Thanks

 

Since you have the 10v coming off of the regulator you need to start tracing it back to the sending unit making sure you have 10v all the way back. That should be he gray wire as described on In the Tank - 240 Volvo Tank Pump and Sender

Start at the cluster end. One of the two roundish plugs has the gray wire. In my Haynes manual that wire is labeled 32/1 - which I believe may be pin 1 of the half circle connector. Does it have 10v? If so, work your way back through the wiring harness.

 

Hey Act,

So get this. With car running, the yellow/red wire in the trunk showing 12.38. The gray wire is giving nothing. The 32 section of wiring is showing interesting results while plugged in. The gray wire is giving off nothing. The blue/red wire (AMP) is showing 12.41 and the brown (PARK BRAKE) is giving 2.38.

I see in the schematic the brown wire finishes its lead at the parking brake switch. Would this low voltage mean there is an issue at the parking brake switch end? I have noticed the light has stopped working recently.

As for the gray wire giving nothing, would that mean the voltage regulator is the culprit, even at 9.91 volts? Or could it possibly be the parking brake issue causing problems to the gas gauge? The problem can't be within the wiring harness because I am not even giving off anything at the cluster for the gray wire. Thoughts?

Also, unfortunately I don't see much online for the parking brake switch. Even for replacement. I would like to see about getting to it. On the schematic it looks like it's inside the parking brake console itself.

Thanks

 

9.91v is within spec for the regulator - so it is working properly. My Haynes manual says it is 10v +- 0.2v - which makes it within spec.

When measuring the voltage on the gray wire in the trunk, are you back-probing it or did you take the measurement with the black connector disconnected? Quoting from cleanflametrap:

"If using a meter, disconnect the plug and measure at the gray wire going into the main harness, and you will measure the 10 volt stable gauge supply (except on the earliest models using a thermal stabilizer, where the voltage will fluctuate). The factory service manual suggests substituting a 68 ohm resistor to check the gauge reads approximately 2/3 full, but a sender problem is rarely one of inaccuracy, it’s just inoperative or intermittent."

So if you disconnect the connector in the trunk and measure the gray wire, you should get ~10v. If you then use a 68 ohm resistor and connect it to the gray wire and ground the other end of the resistor, you should see approximately 2/3 of a tank on the gauge. If this test fails then there is some issue between pin 1 of the half circle connector and the little connector in the trunk.

With regards to the parking brake wire (pin 2 of the half circle connector) giving 2.38v, is that with the parking brake set or is it not set? If the parking brake is set, then I would expect that pin to be 0v.

 

I believe I have checked it disconnected and there was still nothing. I will double check though. But how would I go about this ohm resistance testing? Just set my multi meter to ohms and then what?

Also, with the possibility of the issue being between the pin and connector, doesn't the cluster itself power the pin? The wire is just strictly for lead between the pin and to the connector for the sender. So would there be any ruling out of issue on the wiring harness or could an issue in the harness be possible with my symptoms?

Thanks.

 

The resistor test is not something you do with your multimeter. To do that you need a 68 ohm resistor - which you could buy at your local Radio Shack. A pack of them costs around $2. In that test you disconnect the connector in the trunk and connect one lead of the resistor to the gray wire that goes into the wiring harness. The other lead of the resistor is connected to a ground point on the car. Then the key is turned to the II position with the engine off. The fuel gauge should register about 2/3 full.

The cluster doesn't lower the voltage on the pin. The fuel gauge sending unit is actually a variable resistor. It basically provides a path to ground for the 10v signal. On a properly functioning sending unit connected to the circuit, the voltage measured at the gray wire will vary depending on how much fuel is in the tank.

 

OK, I will try this ohm test and get back with you.

Also, doesn't the cluster power the gray wire via the voltage stabilizer?

I also know that my sending unit is fine because I pulled it from a working 92 240 in which the fuel gauge had always worked. So I believe the issue is with the wiring. Like I said before there were times when the gauge jumped and even worked for a few seconds. Maybe I need to look into cleaning the pins but worst case there may be an issue with the circuit board area powering the fuel gauge. All fuses are fine giving off voltage.

Thanks.

 

I doubt that it is an issue with the cluster since you said that you measured 9.91v on pin 1 of the half-circle connector. My thinking is that if indeed the sending unit is good, you may have an issue in the wiring harness.

When performing the resistor test, I would first perform the test at the back of the cluster. Disconnect the half-circle connector and connect one end of the resistor to pin 1 and the other end to ground. Leave the speedometer connector still connected as that is where the cluster gets its power. Turn the key to the II position and the gauge should read 2/3 full (approximately). If it passes that test, you have eliminated to cluster from the problem and you can perform the same test at the connector in the trunk.

 

Act,

I meant to ask you about the resistor test. Can I just touch the leads of the resistor or will I need to do more?

I have also had the speedo unconnected because the previous owner broke the plastic lock and had it holding together with some black goo. Apparently on these models the speedo cable is short and is suppose to be disconnected before pulling out the cluster. So with you saying I need it plugged in I will need to fix that asap. But does the speedo being connected matter even when testing in position II?

Also, I don't know if this is coincidence but I tried to find where the harness runs and it is literally within the body of the drivers side well area following from trunk to front. I pulled the trim but it seems as if it is literally within the body. It runs from the trunk through a hole and then I believe it runs under the floorboard. The only way I know this is because I have some rotting underneath the driver seat area and see a black sheath covered wiring running there. I don't know if this is coincidence that there is an issue with my gas gauge and then there are openings where possibly this wiring is running. I am unsure if this gray wire is apart of that but I believe the wire runs from the trunk to the cluster right? Any thoughts?

Thanks

 

You can just touch the resistor against the pin but you will have to hold it there for a few seconds cause the gauge is a bit slow to respond.

I didn't know that the '85 had the mechanical speedometer yet. I am more familiar with the all-electronic cluster. In my instructions I had stated to leave the speedometer connected. The reason I had included this is because the later model clusters receive their power through the speedometer connection.

For yours, you need to make sure the cluster has power prior to performing the resistor test. It would be best to be able to provide the 12v & gnd without having the gray wire connected. Don't know if that is possible.

Yes, more than likely the gray wire runs in the sheathed harness to which you are referring. I've never traced the routing of this but I always assumed it ran along the driver side rocker panel.