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vans engine instruments failed

N333M

Active Member
I am about beside myself. Yesterday, I was trouble shooting a vans oil temp gauge in my RV-9 that had been giving me readings I did not believe. After checking the connections, removing the sender unit and inspecting , cleaning and reinstalling the wire, and checking the ground connections. I attempted to start..being cold, and the battery a bit low, it would not start..I hooked a small portable battery booster to the battery, and started the engine. While waiting for the engine to warm up, and see if it was going to register temps, with the engine at idle of about 1000 rpms, I switched the alt field off, and then back on, at which time all the vans stock steam gauges promptly fell to zero. This includes the oil pressure, tach, volt meter, amp meter, both fuel gauges and even cht ..which were just begining to register. and fuel pressure. ARGHHH.. IN other words..ALL the gauges, with the exception of my Garmin G-5, and the gps (which is powered by cigar plug)..These two soldiered on uneffected.
NO Circuit breakers were popped. After cussing myself for this obviously dumb move, I shut the engine off and began to examine behind the panel.
This panel is fairly standard in the old school way, and wired according to the manual I received when I bought the machine.(I didnt build it).
To my consternation, I can find nothing wrong behind the panel..12 vlts on all the gauges with the master on..grounds all good..I have even made jumpers and grounded to alternate spots, think with 12 volts on the gauge..I must have lost a ground..nothing helped.
Did I fry all those vans gauges? ALL at the exact same time..with nothing else affected? Seems a far reach to me..but what do I know?..Less every day it feels like! Any suggestions welcome, including chastising!
Help!
 
Van's gauges are very easy to troubleshoot. If you don't have the procedure that came with every gauge, you can download them on Van's website.......The tests will quickly tell what failed.
 
Really?..I actually never thought of that. I assumed that with 12 v to the gauge, a good ground..with the signal wire attached they oughtta work.
ILl go look at vans site now..
thx!
 
gasman, Im having a difficult time finding the gauge troubleshooting directions on vans site. Any Idea where they are?
Thx
 
Power or ground

Mine has a switch breaker and sometimes this same thing happens. It does not pop the breaker, but there must be a touch of a bad connection. Just turning the switch off and on fixes it. Most likely all of your gauges are powered and grounded together. Loosen, wiggle, and tighten. Most likely they'll work fine...
 
Ggod thought. I just had a 500 hr Potter & Brumfield 10amp breaker fail. This was a straight breaker and not even a circuit breaker switch. It never was cycled for any reason. Prior to finding the problem all manner of complicated troubleshooting ensued with the prospect of high cost component replacement. Then a good friend chimed in and said to bypass the breaker as that was easy and if it solved the problem breakers are cheap. He was right and all manner of frustration and dire expense gloom disappeared. The original breaker would work fine when cold at low load and then conk out after a few minutes.

That flew in the face of my, "Start with the complicated expesive stuff and work my way down towards the easy, cheap, basic stuff", approach (sarcasm). Sheesh.

So start with the basic power and grounds. The under/over voltage or whatever spike event that took down the array of gauges might have been the last straw for one problematic breaker or cheesily crimped ring connector. Or other weak link. Bad grounds are particularly incedious.

Jim
 
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Gents, all this makes perfect sense. However the first thing I did was put the fluke meter on the back of each gauge, and there is 12 volts to the gauges,,and yes..they are wired together. The power feed attaches daisy chained to each breaker, and likewise the grounds. So I have power to each one, and the ground is good, I even took a separate jumper and grounded it to a known good ground, and tried a few of the gauges..like the volt meter, and the fuel quantity..all to no avail...
 
If power and ground are good and polarity is correct, jump one of the sender wires to ground. Try oil pressure if it's easy to get to. It should peg that gauge. It won't hurt the gauge it's how they work. Resistance to ground. If the gauge doesn't change go directly to the back of the gauge and jump sender wire to ground. If the gauge doesn't move the gauge is bad. Since you're not the builder it could be the builder installed a connector common to all these gauges?? Hard to believe they all gave up.
 
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Gents, all this makes perfect sense. However the first thing I did was put the fluke meter on the back of each gauge, and there is 12 volts to the gauges,,and yes..they are wired together. The power feed attaches daisy chained to each breaker, and likewise the grounds. So I have power to each one, and the ground is good, I even took a separate jumper and grounded it to a known good ground, and tried a few of the gauges..like the volt meter, and the fuel quantity..all to no avail...

I would do the same thing with the power wire as you did with the ground wire. Getting voltage is a good test, but making sure the voltage will provide the amperage needed is the more important part.
 
BATT/ALT Master Switch

While waiting for the engine to warm up, and see if it was going to register temps, with the engine at idle of about 1000 rpms, I switched the alt field off, and then back on, at which time all the vans stock steam gauges promptly fell to zero.

Always go back to the last thing you did.

In a Piper Cherokee I had this switch go bad, in fact it wasn't even supposed to be in my airplane. Some old school owner had it installed.

Check your battery fluid. Is it low? The switch you describe can drop watts across the contact points. This sends a message to the regulator to charge the battery. Basically cooking it.

On my Cherokee this caused the battery to be over-charged on long flights. The battery then failed. All fluid in the battery "boiled" off, on a long trip from Alaska to Idaho.

Indications: Lights go bright and then dim, Nav-radios =failure first; then avionics, hot wire smell...

Your switch might be where the loss of current is.

Best regards,
Mike Bauer
 
By any chance are you using an EXP2Bus? When they see an over-current they will cut out but still allow 12V through at very low amps. You will get a voltage reading, but there will not be enough current to power up the gauges.
 
Look at the schematic. All the sender wires go through the sender to ground. Just jump the sender wire to ground, engine first. If the gauge doesn't move go to ground on the airframe. If the gauge moves when grounded to the airframe and not the engine, the engine ground to airframe ground may be open. Depending how the ground circuit is wired it is possible for engine ground and gauges to be on separate ground circuits. If neither of these jumpers to ground work, go directly from the back of the gauge going to the sender to the same ground you checked at the instrument that is known good. If the gauge responds you have an open ground between gauge ground and airframe. I do this junk all the time.

Or, run two jumpers. One jumper gauge ground to engine the other jumper sender wire from gauge to engine ground. both can be grounded anywhere on the engine. Gauge should peg. If it does peg, remove ground from gauge ground. If the gauge comes back down there is an open gauge ground to engine. If it stays pegged, remove sender jumper to ground. If it comes back down sender wire is open.
 
Dont know what an EXP2bus is, so I cant answer that. As I mentioned, I am not the builder, and my experience behind this panel previously has been only to remove a couple of bad flight insturments and replace them with a garmin G-5.. which btw,,is running just fine on the same power connection. As well as the Ifly GPS thu the cigar plug via a breaker. All were on at the time of the failure of the engine instruments.
 
Thanks men..I grounded the sender wire to the ground post on the back of several of the gauges..nothing..gauge does not respond. Has 12 v on the power wire. Ran a jumper from known good ground on firewall to sender post on gauge..no response..arghh.. as I feared..looks like all these gauges failed..at the exact same moment.. ok..my upgrade to an EIS is going to be a bit sooner than spring or summer, as I had planned.
Dont think Im going to buy any more of these 37 dollar gauges.

NOw..I just have to understand why they all quit when I switched the ALt field off, and back on..and didnt pop a breaker..I obviously wont be checking the alt that way again, but I have done that before.
The battery booster I had hooked up to the low battery is one of those small lithium schumacher portables.. trying to understand if that somehow caused this..and the Garmin G5 and Ifly 740 were just better able to stand some sort of surge..being unaffected.
 
NOw..I just have to understand why they all quit when I switched the ALt field off, and back on..and didnt pop a breaker..I obviously wont be checking the alt that way again, but I have done that before.
The battery booster I had hooked up to the low battery is one of those small lithium schumacher portables.. trying to understand if that somehow caused this..and the Garmin G5 and Ifly 740 were just better able to stand some sort of surge..being unaffected.

Breakers trip from current flow above the value they are rated for.
Voltage, on the other hand has no influence on whether a breaker will trip (assuming it doesn't go below the nominal range) but it can have a detrimental effect on some electrical equipment if the voltage gets high enough (even for a short moment), including the Van's brand gauges.
 
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