View Full Version : No Voltage Stabilizer on Late Series 3?
jac04
10-11-2009, 03:31 PM
I'm re-installing the instruments on my late Series 3 Air Portable. This vehicle should use the same fuel and water temp senders as a civilian S3.
Now, there definitely was NOT a voltage stabilizer installed on this vehicle, and there was no sign whatsoever of there ever being one. The green wire feeding the water temp and fuel gauges comes off of the fuse block and goes directly to the gauges. Is this normal?
All the wiring diagrams I have shows that the green wire should go into the voltage stabilizer, then a light green wire should come out and go to the gauges. I have the stabilizer and was about to modify the wiring when I thought that I better check with the experts.
What should I do?
scott
10-11-2009, 04:36 PM
Maybe the green wires went to the stabilizer and when removed the light green wires went with it so the greens were just plugged into the gauges. I've got an old post here somewhere where I made my own v s for a couple of bucks
jac04
10-11-2009, 05:17 PM
There is no sign of there ever being a VS. The area on the speedo where it mounts has no indication. Also, ther green wire is set up with 3 daisy-chain connections (presumably for fuel level, water temp and oil temp, although I do not have an oil temp gauge).
brucejohn
10-11-2009, 05:54 PM
jac04 since most of my truck in pieces right now, I pulled my instrument cluster (82 SIII 109) to look. I have a green w/ blue stripe straight from temp sensor to lower post on gauge. Light green from top post temp gauge to top post fuel gauge and then down into loom. Green w/ black stripe to straight to fuel sender.
Now I am new to these trucks. I also have a light green wire coming out of the loom attached to a rusty rectangular item attached to the back of my speedometer. Voltage stabilizer?
On the Land Rover UK Forums there's a retired military mechanic that has a few Lightweights goes by Ruxy
Later GS 12 volt Lightweights did not have a voltage stabilizer , uncertain of change point but probably about 1980
picked quote out of thread
http://forum.landrovernet.com/showthread.php?t=163110&highlight=lightweight+voltage+stabilizer
So I'd say it depends :p on what year vehicle you're dealing with and what gauges have been fitted.
jac04
10-11-2009, 06:52 PM
^^ Interesting stuff.
When I bought my Lightweight, the temp gauge read in the red, but the temp was checked with a thermometer according to the PO and the temp was OK. At least that's the story I got.
I think what I have is a 1983 Lightweight (11" front brakes, metric brake system). The original gauges (fuel & water temp) are fitted. I also believe that the fuel level senders are original. However, I have fitted a new 560794 water temperature sender. Does this mean that I need to have a VS in the water temp gauge circuit since I am using a 'normal' temp sender? I'm not sure, because the difference may be in the actual gauges. Hmmmm.......
jac04
10-11-2009, 08:45 PM
OK, here's some more info. From what I gather, the voltage stabilizer provides a voltage to the gauges that is lower than battery voltage. I have read that this voltage is both 10 volts and 8.5 volts. I don't know who to believe. I don't have a battery yet, so I couldn't measure the output voltage of the stabilizer.
However, if I hook up a 9 volt battery to either the fuel gauge or the temp gauge, the gauge rises to either the "full" or "hot" position. Since I know that the fuel sender has no resistance at the full level, this means that I definitely need less than 12 volts to produce an accurate gauge reading. Does this sound reasonable?
What happens when you hook 'em up to 8 AA, AAA, D, or C batteries in series? Battery voltage when hooked up in series ( + batt-+batt-, etc) is additive. Alkaline battery voltage is 1.5 VDC (printed on side of battery). NiMH is 1.2 VDC.
Are there an Ohm numbers on the gauages?
kevkon
10-11-2009, 09:50 PM
It's really a voltage regulator and it is meant to provide 10.5v to the gauges as opposed to the 14v supplied thru the charging circuit.
jac04
10-12-2009, 07:09 AM
Nium-
No ohm numbers on the gauges that I saw, but I didn't remove the individual gauges from the main round gauge.
My next step was to try different voltages to the gauges. Either that or I will just install a battery and move the fuel sender to different positions and see what the gauge reads.
kevkon-
It is actually called a voltage stabilizer according to Land Rover.
jac04
10-12-2009, 07:14 AM
jac04 since most of my truck in pieces right now, I pulled my instrument cluster (82 SIII 109) to look. I have a green w/ blue stripe straight from temp sensor to lower post on gauge. Light green from top post temp gauge to top post fuel gauge and then down into loom. Green w/ black stripe to straight to fuel sender.
Now I am new to these trucks. I also have a light green wire coming out of the loom attached to a rusty rectangular item attached to the back of my speedometer. Voltage stabilizer?
brucejohn-
The light green wire should go to the voltage stabilizer, and it sounds like that's what it is going to. Is there another wire (green) going to the VS?
According to the S3 manual:
Green -->VS-->Light Green-->Fuel gauge-->Temp gauge.
The Green wire should be key-on power coming from the fuse block, and should be connected to the "B" terminal on the VS. The Light Green wire is connected to the "I" terminal.
kevkon
10-12-2009, 07:43 AM
The green wires are power and need to come from the voltage stabilizer. The green/ ---- wires go to the sender. Any gauge operating at 10.5v needs to fed thru the stabilizer.
Walker- Yes it's called a stabilizer, but it really is a regulator. I think the reason they called it a stabilizer is because the gauges operate in a more stabile manner at a steady 10.5v.
brucejohn
10-12-2009, 08:15 AM
jac04...
I will check what is coming in to the stabilizer when I get home tonight, I don't remember it as green?
Going the direction you listed:
V/S > light green > loom > light green > fuel gauge upper post > light green > water temperature gauge upper post.
Fuel gauge lower post > green w/ black stripe > loom > fuel sender
and
Water temperature gauge lower post > green w/ blue stripe > loom > engine block temperature sender near thermostat housing.
That all appears to match the diagram available from our hosts :) Finally, something on my SIII as it should be! WooHoo! Maybe working on the wiring won't be so bad?
Walker- Yes it's called a stabilizer, but it really is a regulator. I think the reason they called it a stabilizer is because the gauges operate in a more stabile manner at a steady 10.5v.
Kevin, jac04 wrote that about stabilizer/regulator not me. :D
jac04 some resistance numbers I found for the temperature sending unit 560794...
Cold 300 ohms
Hot 45 ohms
If that helps any.
jac04
10-12-2009, 12:38 PM
Nium-
Where did those resistance numbers come from? My brand new Genuine 560794 sender reads higher than that at room temp.
Anyhow, I hooked up a car battery to the system "as-is" with NO voltage stabilizer in the circuit. The fuel gage tracked perfectly with the sender position, and the water temp gauge read a little over "N" at 173 F.
Note that the water temp test was done with an old sending unit that showed less resistance at room temp than my new one (don't know why, they are the same part number). I will need to pull my new temp sender from the head and use it for my test. I expect this to produce a slightly lower gauge reading for the same temp. My thermostat is 179F, so I expect this to produce a reading in the middle of the "N" range.
So, things seem OK without the stabilizer with a constant 12 volts. Next, I may install the stabilizer and see what happens....or just put everything together and not worry about it.
Nium-
Where did those resistance numbers come from? My brand new Genuine 560794 sender reads higher than that at room temp.
I did a number of searches on the Land Rover UK Forums and a couple of different posts stated that was the resistance numbers people had measured. If you've got yours working then :thumb-up: and don't worry about it.
brucejohn
10-12-2009, 01:10 PM
If the stabilizer is a "regulator" wouldn't the purpose of having it in the system be to keep the meter readings consistent throughout the varying conditions of driving? While they may work without, I seem to remember a science class in high school where we studied the importance of both accuracy and consistency throughout our measurements?
Sorry, I am spouting off.
jac04
10-12-2009, 02:15 PM
^^ Yes, true. I'm still wondering what is different about the late Lightweights that were not factory equipped with a voltage stabilizer. Are the gauges different? Is there something else that keeps the voltage to the gauges constant as the system voltage changes?
jac04
10-12-2009, 07:45 PM
In case anyone is interested:
I tested the fuel gauge and water temp gauge again tonight with no voltage stabilizer. The gauge readings were not affected by any change in the supply voltage to the system. I first tested with a 12 volt battery hooked up with a supply voltage just over 12 volts. I then connected my battery charger to the battery and the result was a voltage of 14.5 to 14.7 volts. The gauges read the same no matter what voltage the system was supplied.
So, no voltage regulator for me (at least for now).
kevkon
10-12-2009, 08:05 PM
As far as I know any Smiths non-mechanical gauge requires the stabilizer/ regulator. You might want to give Nisonger a call if you are thinking of running them without.
Les Parker
10-13-2009, 08:20 AM
My understanding is that the stabilizer smothes out any spikes in the info sent by the transmitters, 12v in 10.2v out (consistently). Thus if you go round a corner,down a steep hill etc. the guages on the dash do not jump out all over the place, as the early IIa's did.
Just my 2p
kevkon
10-13-2009, 08:42 AM
Les,that's what my understanding is as well. As I said, I believe that's why they termed the device a stabilizer. I'd still give Nisonger a call to see if any damage to the gauges can occur if the stabilizer is not used. We are talking Lucas electrics here, so anything is possible.
jac04
10-13-2009, 08:59 AM
Remember, this vehicle did not have a voltage stabilizer to begin with. It's not that someone removed it - it never had one from the factory.
This corresponds to the info found by Nium at:
http://forum.landrovernet.com/showthread.php?t=163110&highlight=lightweight+voltage+stabilizer
Things seem to be OK so far without the stabilizer, and the fuel gauge responds fairly quickly, but it does not "jump around" if I quickly move the float on the sending unit.
Also, the stabilizer supplies the gauge circuit with a constant voltage. How does this 'smooth out' the variable resistance of the sending unit? It doesn't. It just gives the gauges a constant reference voltage.
My gauges are unaffected by any change in reference voltage, so why would I need a stabilizer?
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