240 Simultaneous 240 temp and fuel gauge problems PLEASE HELP!

Hi all,

still having simultaneous problems with my temperature gauge and fuel gauge showing low readings, even when the car is run for some time with plenty of fuel. They both move a small amount.

I have had some great advice from others on the volvoforums.org.uk forum suggesting it could be the voltage stabilizer. I have been given three voltage stabilizers by Bob the parts chap at Braydon Motors, thanks Bob, and fitted them one after the other and still no readings. The parts were second hand but I wouldn't have thought all three were kaput, I thought at least one would have worked.

It was suggested the problem could be a ground problem, what would I have to ground on the cluster? do I ground the metal that the voltage stabilizer is screwed onto?

This is driving me nuts, just want it sorted, might have to resort to fitting a second hand cluster that I know works.

My car is a 1991 SE 2.3i Estate

All suggestions would be grateful.

Paul from the UK

zagatoman said:

temperature gauge and fuel gauge showing low readings
...voltage stabilizer

Click to expand...

I have no knowledge of your board:

1. If printed circuits exist on this board, can a temporary jumper wire go from voltage source output to both gauges' input?

2. On traditional fuel/temp gauges, they work via ground potential from fuel/temp sending units. If true, and for fuel tank, have you checked fuel tank's ground, and cleaned it up back there? But, if both your fuel/temp gauges are showing a lower reading, this most likely is not an issue.

Thus, logic would suggest there is a power loss on your circuit board if traditional fuel/temp gauges get their ground potential from each respective sensor.

Without a schematic, I know nothing specific about your setup.

The gauges work off of variable resistance senders. The sensor works through ground and the gauge itself has a ground for its operation. Your cluster may have an open ground circuit as suggested. I like that suggestion as well. The voltage regulator is connected to 12V input, ground and the regulated 10V output which goes to power the gauges.

If you are comfortable with a volt ohm meter then you can trace the circuit out and make sure you have continuity between the gauges and the regulator. Then make sure the gauges have a good ground circuit. The screws that hold the gauges on are also connections so that may be the open circuit your gauges have.

zagatoman said:

Hi all,
still having simultaneous problems with my temperature gauge and fuel gauge showing low readings, even when the car is run for some time with plenty of fuel. They both move a small amount.
- SNIP -
This is driving me nuts, just want it sorted, might have to resort to fitting a second hand cluster that I know works.
My car is a 1991 SE 2.3i Estate
All suggestions would be grateful.
Paul from the UK

Click to expand...

http://forums.turbobricks.com/showthread.php?t=207465
read and heed POST #1
SCROLL DOWN to POST # 19 follow directions
Download 240 wiring diagrammes
open pdf file for 1991 240 diagrammes
pg 16 (Figure 5 "Instrument Cluster")

*first thing* is to check all harness connections
next pin out voltage TO THE CLUSTER
read voltage @ the "stabilizer"
clean FUSE CONNECTIONS at the fuse panel
check for *small black wire* adrift near the cluster..(nominal CLUSTER GROUND)
here is a nifty "variable source" for GAUGE TESTING:
see: http://www.clarks-garage.com/shop-manual/elect-19.htm#coolant

fuel level resistance:
EMPTY 240 Ohms
1/2 tank 130 Ohms
FULL 33 Ohms

temp sender resistance:
50*C = 122*F 282 Ohms
100*C= 212*F 60 Ohms
120*C = 248*F 40 Ohms

go here and download the GREENBOOK listed below:
http: //www.k-jet.org/documents/greenbooks/200-series/
grab: TP11402-2 Electrical System & Instruments (excl. wiring diagrams) Repairs and Maintenance 242 / 244 / 245 1976- All Pages

starting at the GAUGES SECTION (pages 57 or so)....testing and values supplied

and Bob's yer Uncle!

First thing I would try is tightening all the screws and bolts on the back of your instrument cluster. The circuit board is grounded through those via the wire harness.

Second. that voltage stabilizer is such a common issue, I wouldn't put another used one in.
New part is less than $30.00 Part #1362674

Also there is another circuit board that will effect both gauges called the temperature compensator , part# 1363117 , its around $50.00.
http://s3.amazonaws.com/fcp-product...s/products/32133/large/1363117.jpg?1294412710

I had this issue, and bought a new voltage stabilizer. Before it arrived, my battery died, and I found out it was actually a bad regulator on the alternator combined with an old battery.

I am struggling with temp gauge (I think!) problems myself - and last night a friend just did this quick test:
"If your coolant gauge is reading erratic, or the needle doesn't move at all, locate the coolant temp sender near the center of the engine block on the driver side under the intake manifold. The wire is yellow, and the connector is a female spade type. Disconnect the wire and touch it to ground and the needle should go to the hot range of the gauge when the key is in the run position. If it doesn't then the temp compensator board is most likely the cause." (Source: IPD, but this is also in Bentley Manual.)
When I had to make a call re: a parts order, the parts guy I spoke with said the same thing - AND - that if BOTH gauges are inaccurate - to look at the temperature compensation board. (Best price I found on that was about $57.)
You should at least be able to rule out the comp board as the problem by doing this - and be able to move on, for sure, to other diagnostics.

My 244 has a similar problem. Temp gauge reads low when the fuel is low, high when it's high.
Unfortunately I can't help, I replaced the gauges with aftermarket.

1983 242 glt.

Just fixed this exact same problem yesterday.
Cleaned and checked all my contacts and put in 2 new gauges.
On the back of each threaded pin on the gauges there is a copper collar....sanded the ends of those.
Temp and gas now working perfect.
I did notice on my circuit board one female spade under those two gauges that had nothing plugged into it.
Any ideas?
Might be a missing ground?

There are unused M quick-disconnect spots on every integrated Volvo instrument panel I've seen and can remember (can't remember the 122 - it's been many years). Don't fret.

If your temperature compensator board is going bad a better idea is to get rid of it and jumper over it. Art has the procedure at cleanflametrap.com (look for "Temp Faker"). Volvo put that in to keep idiots from complaining to the dealers that the temp guage was wiggling.

Searched for the original Volvo PartNumber for this Voltage Regulator in TB and found this thread.

While Tasca and others want $30 and more for this thing, you can get a more precise equivalent from Mouser & Digikey for under $1.
The original is no longer produced, this replacement is 2-3 generations newer and has better characteristics.

http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/KA7810AETU/?qs=%2fha2pyFaduhX7zsYOe4LUTdAZibOoUY4A%252biCI5vlJFM%3d
or
http://www.digikey.com/product-search/en?KeyWords=KA7810A&WT.z_header=search_go
and
The TO-220 format is popular, so theres a huge variety of coolers.
http://www.digikey.com/product-search/en?pv98=2&pv98=113&FV=fff40012%2Cfff80068%2C5940002&k=to-220+heatsink&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

Noteworthy difference:
Pin1 and Pin3 are reversed on the newer replacement!
You have to insert it upside down.

Double02 said:

I had this issue, and bought a new voltage stabilizer. Before it arrived, my battery died, and I found out it was actually a bad regulator on the alternator combined with an old battery.

Click to expand...

I am getting suggestions from fellow 240 owners that my random stalling may also be related to a bad regulator. Did you replace just the regulator on the alternator, or did you do the whole alternator?

Double02 said:

I had this issue, and bought a new voltage stabilizer. Before it arrived, my battery died, and I found out it was actually a bad regulator on the alternator combined with an old battery.

Click to expand...

I can confirm this because it just recently happened on my Volvo 240 when the voltage regulator went bad. My battery was good. Installed a KAE made in Germany voltage regulator, and every thing is fine now. The KAE are half the price of a new Bosch. Don't know yet about the durability of the KAE.

The temp and fuel gauge would just barely wiggle randomly, and then go back to their starting position. What I mean by barely wiggle is the indicator needles were not moving no more than a 1/32 of an inch or round about that much.

janikphoto said:

I am getting suggestions from fellow 240 owners that my random stalling may also be related to a bad regulator. Did you replace just the regulator on the alternator, or did you do the whole alternator?

Click to expand...

I just replaced the voltage regulator/brushes on the alternator. 13.9 volts now across the battery on a 1990 Volvo 240.

Hi,

I had been having issues with my temp and fuel gauges mis-reading. Never knew when the tank was empty because the gauge never went down that far, which means the gauges were getting too much voltage for whatever reason. Recently my alternator failed, car almost died 2 mins from home. I smelled a nasty electrical burning smell from the dash and it freaked me out. Confirmed alternator was pooched, and replaced it. Battery charging as normal now. Drove the car a few days and again smelled the electrical burning smell from the dash. Freaked out, worried that I wrecked the new alternator. A few days later I started the car late at night on one of the coldest days of the year, in January, in Ontario, Canada where I am. The car started briefly and then with a jerk came to an abrupt stop. Would not start and had to be towed home.

I started to tackle the issue by diagnosing and found that I had spark and fuel and that my timing must be way off. Confirmed that the belt slipped, as it was so cold and stiff and the tensioner was rusted, so it wasn't tensioning properly. Re timed the car and it started right up.

Simultaneously I pulled the instrument cluster from the dash and took it apart to address the burning smell and faulty gauge readings, and to replace a dash light. I found a melted resistor in line with the voltage regulator that takes battery voltage down to 10v and sends to the fuel and temp gauges. Smelled the area and sure enough it smelled exactly like that nasty electrical burning smell. I took out the resistor and tried to figure out what Ohm reading it should be. It looks like 90ohm?

Next I tested the voltage regulator / transistor and found that it had been outputting correct 10 volts but that it was getting extremely hot. It burned my fingers within seconds of receiving 18v from two 9v batteries. Must be faulty and getting so hot that it melted the in line resistor. Thus giving too much voltage to the gauges?

My theory is that in the process of the alternator dying, voltage spiked, resistance got so high that it fried the voltage regulator and in turn that fried the resistor.

I sourced a new NTE 10v linear voltage regulator on eBay here: https://www.ebay.com/itm/NTE-NTE1953-IC-Vltg-Reg-Pos-10V-1A-Low-Dropout/200404969310

Which has the pins reversed of course, so I had to put it in backwards. Then I found a 100 Ohm 1/2 Watt resistor (can't find a 90 Ohm anywhere) and soldered it in place. I tested the temp and fuel gauges with a 9v batt and they go up fine. Put the cluster back together and made sure the voltage regulator is outputting 10v, it is. New regulator does not get hot at all. Turned the key and the fuel gauge goes up. I cant remember how much fuel was in the tank but I still suspect that my gauge is reading too high. It's at about 3/4. Maybe the sender unit has failed? And is not providing enough resistance to pull the gauge down? My temp gauge is also kind of high. It's at about 9:30 when the car is warmed up. But I did put in a higher temp thermostat so maybe that's correct.

To add confusion when I put the cluster back in now the Oil warning light will not come on. I figured must be a bad solder joint that I messed up when taking it apart. I grounded the oil sender wire near the alternator and checked the light again. It turned on. So now my oil sender has gone bad. Easy fix but man the list never ends.


Does anyone know what the value of the resistor on the cluster circuit board should be? 90 Ohms? Would this affect my fuel gauge?

Here's a pic of my old melted resistor:



As you can see, it got pretty hot

And here's a pic of the original voltage regulator:



It is an ITT TCA700Y made in Germany, also used in Volkswagen's

Hard to find now, but they are out there.

It's a 10ohm (BRN-BLK-BLK) resistor. In the circuit, it's in series between the center ground pin of the regulator and ground. I haven't seen this circuit configuration before -- maybe it's trying to compensate for the gauge characteristics?