VDO Oil temp and pressure gauges won't respond!

[Windisch]

Just installed the current VDO 'Jet Cockpit' gauges in my 73 bug, carefully wired them up and found to my chagrin that neither of them indicate a response. [The oil temp sensor takes off from an oil sump plug sensor/sender and the oil pressure sensor takes off from the usual twin connector sender that plugs into the the standard oil idiot light port on the engine case.]

The shared power wire for the gauges runs from an accessory (Pos+) wire connected to the car's kill-switch (it in turn connects to a separate, new 5 AMP fuse, and from there to the gauges) and the shared GRD wire attaches to an under-dash metal screw. With the kill-switch ON and the ignition started, I expected to see at least an oil pressure readout (the oil temp readout should indicate after the car has run for a few minutes, presumably).

After a 10 miles test run, still absolutely no indication that either gauge is responded optimally! The only thing I can figure is that the fuse might have been bad, so I changed it out w/a new one: same 'no response' result!

Obviously this is one of those perplexing problems where in order to shed insights on the problem properly, one needs to be able to visually examine the installation, but no one anywhere near me is qualified (or motivated) to take a detailed technical look at things. Therefore, I'm just fishing around for any suggestions and/or helpful hints as to where my difficulty might lie from others who may have already been down this thorny path before!

It's hard to adequately describe the frustration of going to all this trouble, following all the diagrams for wiring properly and then getting a great big fat ZERO/ZED/ZILCH as a payoff! Grrr-grrr! These are brand-new gauges.
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1973 Standard Beetle, 1974 VW/Porsche 914-4, 1.8 liter
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Der Volkswagen ist ein Ausdruck der deutschen Kultur der Allrad Art ...

[The only irrefutable evidence we have that intelligent life truly exists elsewhere in the Universe is the fact that so far it has NOT contacted humanity...]

[slayer61]

Sorry to hear. I'm not really familiar with your gauges. Instrument power aside, most of them use a variable resistor for the sensor, or sending unit. That is to say there is "variable" resistance to ground, based on what they are monitoring, or measuring.


Do one at a time... Take the sensor wire off of the sending unit and connect it to ground with jumper wire, alligator clips... something. Your connected gauge SHOULD go to maximum all other things being correct. Good luck, Sir.
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[74 Thing]

Take out your volt meter and make sure you are getting 12v to the gauges when switched on, but most likely it is your grounds. Get a spare wire and run it to a good bare metal to see of the gauges work.

[Windisch]

[Cusser]

Sounds to me that you have the issue narrowed down, just need to get positive voltage from the fuse box to the gauges.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[slayer61]

Congratz OP. You did it!
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[Starbucket]

What does your "Kill switch" kill? If it's grounding the coil, that's not 12 volts so just pick one of your existing fuses (there is usually an open one at the end of fuse block) and use it if it's switched on/off with your key.

[Windisch]

[Windisch]

[Windisch]

PS: Haven't yet gotten around to tracking down that PWR problem with my VDO gauges but I did install a new gauge today. It's a 1944 German Luftwaffe altimeter from a Messerschmitt and it's in perfect, functional condition. Since I belong to a WW2 Luftwaffe historical re-enactment group, I've had a similar Lufty altimeter in each of my VWs (Type 1s, Typ 182s, Typ 2s and Typ 4s). It is a curious little bit of eccentricity but it definitely makes 'Brumel', my 73 bug, stand out from the crowd. Pictures attached. Hals und Beinebracht!

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1973 Standard Beetle, 1974 VW/Porsche 914-4, 1.8 liter
----------------------
Der Volkswagen ist ein Ausdruck der deutschen Kultur der Allrad Art ...

[The only irrefutable evidence we have that intelligent life truly exists elsewhere in the Universe is the fact that so far it has NOT contacted humanity...]

[Maddel]

[Windisch]

[VW_Jimbo]

Now that is a modified Bug! Has got to be fun! Still a 4 seater?

Does much air get in through the ragtop? Thinking of putting one in my F22! Give it a vintage feel!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Windisch]

[Starbucket]

Looks like a front engine prototype beetle to me.

[Windisch]

Finally: Problem resolved! As everyone predicted (correctly) and as simple logic implied, the lack of PWR to the gauges was today traced to a simple and rather common wire splicing connector that most of us use at one time or another! The culprit is shown in the attached image (or at least one identical to it). Since the two wires were...main feed 14 Ga and gauges run-off wire 16 Ga...two different sizes, so when I vice-gripped the metal connector bridge shut, it somehow didn't make contact with the smaller wire. A great example of several familiar aphoristic situations: 1) It's usually something trivial and therefore easily overlooked or dismissed; 2) always check such components for integrity when a wire spliced-in doesn't carry the intended charge; 3) Cusser's 90% Electrical Idiots Fraternity is NOT a small and highly select club!

Problem is now solved and my gauges are registering values correctly (although I am beginning to suspect that the engine oil temp readout of 3250 degrees F. is slightly in error...d'ya think?)

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1973 Standard Beetle, 1974 VW/Porsche 914-4, 1.8 liter
----------------------
Der Volkswagen ist ein Ausdruck der deutschen Kultur der Allrad Art ...

[The only irrefutable evidence we have that intelligent life truly exists elsewhere in the Universe is the fact that so far it has NOT contacted humanity...]

[MTT3107]

I have given up on those splice connectors....

Tried using them a few times, still have a box full of them...
Using them was always "hit or miss"..

My bug is a '73, I guess is that the insulation on my 50 yr old wires is just too hard and brittle for the blade to cut through.. I have broken a few of them attempting it.

So now I cut the old wire, splice in the additional one, and solder the whole thing, cover it with shrink tube.

Takes a lot longer, yes, but makes for a reliable connection.

[Cusser]

[Windisch]

[Windisch]

OK. A question for you who are VDO gauge hook-up cognoscenti. I finally got my VDO oil temp and pressure gauges 'powered up' (the fault was in a faulty PWR wire splice connector, as above) and took the bug out for a test flight today.

The oil pressure gauge started off registering 60 PSIG of pressure (cold engine) that over the course of an 8 mile run, dropped to about 20-30 PSIG (at speed) and to about 10 PSIG at idle (at stoplights). The oil temp gauge (which uses a sensor attached to the case's oil relief valve orifice), the scale of which begins at about 130 deg F, and goes up to about 300 deg F, never did rise above the 130 PSIG starting value. I use one of those two-signal senders (one for normal oil idiot warning light and the other for the oil pressure gauge) and, as just mentioned, an oil pressure relief valve sender for oil temperature.

When I got back home at the conclusion of the brief run, I noticed that there was a small amount of engine oil on the engine metal just below where the oil pressure sender unit screws into a 90 degree angled brass fitting, inserted in the case's stock OEM idiot light sensor orifice.

OK. No real mystery here, I am thinking. The brass 90 degree angled case elbow (which is actually a 'T-fitting' with a cap on it) is leaking...either at the screw-in cap or on the male screw threads where the elbow screws into the case port.

So here's my question for y'all: In order to prevent leaks of this sort (which pretty obviously resulted in my screwy oil pressure readings, as far as logic and deductive reasoning may determine), what does everyone do about leaks of this sort. Does one use Teflon tape on the threads or what? Also, does having an oil washer on the thread screw-in (on the case) make a huge difference or not? My oil washer somehow got misplaced, so I screwed the brass fitting in w/o it.

[The correct explanation and resolution solving this minor glitch for me gets a gen-u-wine hand-knitted and crocheted bath tub made by my 110-year- old, near-sighted and nearly blind grandmother (and my Husky dog has also promised to throw in one of his favorite doggie treats, as an added incentive! Woof!]

I'll continue try to figure out why my oil relief valve sender isn't registering any temperatures...unless someone has a suggested cause for that perplexity, also.
_________________
1973 Standard Beetle, 1974 VW/Porsche 914-4, 1.8 liter
----------------------
Der Volkswagen ist ein Ausdruck der deutschen Kultur der Allrad Art ...

[The only irrefutable evidence we have that intelligent life truly exists elsewhere in the Universe is the fact that so far it has NOT contacted humanity...]