Hi All

I just bought a used 1993 240 Wagon (245) and the temperature gauge seems to be unreliable. Driving the vehicle the second day I owned it, the needle shot right up to the red zone. I immediately pulled over and checked the coolant and belts. Everything was fine.

Today, Day 3, the needle is barely above the bottom. Is there a history of problems with the temperature gauge and what is the best plan of action to troubleshoot the problem.

Thanks for any help!

TK

TK --

Since the others gave away the secrets, I'll neither agree nor disagree. But the voltage regulator could also cause erratic behavior (though you'd expect the gas gauge to also misbehave).

These pix are from my '86.

Don Foster (near Cape Cod, MA)

Don, I have this same problem (after hanging on this Brick I realize it's common) Can I get to compensation board from under the dash? It looks like the front has to come off from your pictures. I can use a hint on pulling aprt the plastic by the gauges IF that's the case.

Tony --

The only way to access the compensating board is to yank the cluster. It's an easy job, but slightly harder on an older car having the speedo cable ('85 and earlier, I think).

On the earlier cars, you must reach up under the dash and disconnect the cable (a 1/4-turn of the collar). On the later cars ('86 and newer) the speedo is electronic, so you only need unplug one extra connector.

Then you sit in the driver's seat, unscrew the four mounting screws, pull the cluster straight out, tip the right side outwards and unplug various cable, tip the left side out and unplug various cables, and then slide the cluster sideways toward the center of the car.

Make a sketch of where each wire or harness attaches to the cluster—unfortunately it's easy to reattach one or two connectors incorrectly, and this will damage the instruments.

With the cluster sitting on your workbench, remove seven screws around the perimeter of the printed circuit board and lift it straight off the plastic housing. This reveals the innards, with all the gauges attached to the PCB. From here you can remove the compensating board.

From my first picture note that the left two screws also secure a metal plate, which acts as a heat sink for the voltage regulator. Be sure you properly reinstall the 3 legs of the regulator during reassembly.

Don Foster (near Cape Cod, MA)

TK,

I just had the same problem and cleaned the temperature compensator board pins and voltage regulator pins (instructions all here in the archives and FAQs) on the instrument cluster and it's been a rock now. No matter what the outside temperature is or how I'm driving, it heats right up to a hair below the little dot and stays there. Betcha a twenty.

Temperature compensation board needs to be swapped. Common problem. I am not sure if any board, 86-on, will do it but I think it might.

I have a '85 244 and had a similar problem. Whenever I would take off and shift into second gear the needle would shoot straight into the red and as I let off the gas it would settle down. Here's where I separate from the experts.

First thing I did was check the wiring to the coolant temp sensor. I believe on your B230F it's below the intake manifold. It should have a yellow wire. There are two sensors, one is for the computer I think and the other one is for the temp gauge. In any case, check to make sure that the wiring is not frayed. What happened to me was that the wire was worn and would ground out on the intake manifold. There are a bunch of wires in the engine wiring harness that travel through the intake manifold and in that area. Upon inspection I found a bunch of other wires that were also in bad shape and needed replacing, particularly the alternator and oil pressure light wires.

Thought this might be a good place to start before you disassemble your dashboard.

Good luck!

Orest '85 244 179k

Orest,

I did forget to mention that, like you, I attached the sending unit connection and checked the wires routed thru the intake manifold area first and that is good advice and is an easy first step.

However, pulling the dash apart does build character, you know.

"...pulling the dash apart does build character..."

It's a very, very easy job. You do it while just sitting around.

Don Foster (near Cape Cod, MA)

"very, very easy job" - yes I guess you are right. Just add beer and I guess you can take the word "job" right out of there.

How about a "(your worst Volvo job ever here) does build character..." contest. My most recent entry would be "replacing your oil pan gasket on a 240 (when you thought it would be a 30 minute job like on your Dodge Caravan) does build character."

Thanks Don - you are the Atlas upon whose shoulders the Brickboard rests. (Don't shrug, OK?)

Robb (in MD - there seems to be another Robb with some bad problems right now but it's not me)

"Just add beer......"

That got my attention!

"...replacing your oil pan gasket on a 240 (when you thought it would be a 30 minute job like on your Dodge Caravan)..."

Yeah, that job's no fun. How about dropping the oil pump into the pan, then removing the pan? And then reinstalling the pan, and then bolting up the pump by blindly reaching between the pan 'n block? Oh, and ya gotta install the delivery pipe blindfolded, too, while ensuring that the O-ring on each end remains intact...

I guess the second suckiest job is the &^@*$% blower motor.

And reinstalling the wiper cables is no fun.

"...upon whose shoulders....(Don't shrug, OK?)"

Objectively, it's tough being the architect of such a Rand-y bunch. Ayn that's no joke!

Don Foster (near Cape Cod, MA)

Just an aside question, mostly on-topic...

Our '93 240 wagon's temp gauge likes to sit a the bottom...ALWAYS. I haven't had a chance to chase it down yet.

I'll probably start at the sending unit. I just got the car and am wading through all sorts of little annoyances.

Ben

Hi Ben, Our 86 240 had the same problem. Replaced the temperature compensator board and it was ok. Go to swedishengineering.com to get very fair priced volvo parts. John

Ben --

The gas gauge is OK?

And the engine appears to reach temperature? (That is, you get adequate heat from the heater?)

If so, I'd check:

• The connection at the temp sensor (in the head under intake header #2)
  
  
• The nuts securing the temp gauge to the instrument cluster PCB (printed circuit board)
  
  
• Resolder the temperature compensating board
  
  
• Clean and tighten the four pins connecting to the comp board
  
  
• Replace the LM2902 quad op-amp and the PNP transistor on the comp board. I've done this (cheap 'n easy) and can discuss the procedure.
  
  

Try this: Unplug the sensor and ground the wire. Does the gauge peg at hot? If so, then the gauge and comp board are likely OK, and the problem's the sensor. If not, the problem is somewhere in the wiring or temp gauge circuitry.

Don Foster (near Cape Cod, MA)