VDO Tach Wiring
- chitwnvw
- Resident Troublemaker
- Location: Chicago.
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VDO Tach Wiring
I am trying to get my VDO tach going. The backside has a positive, negative, ground and light spade.
First, what's the difference between the ground and the negative spade?
I have wired the positive to the coil and ground the negative. With it wired this way the car won't start. Why?
Now if I start the car and hook the tach up this way it reads correctly.
What am I doing wrong?
First, what's the difference between the ground and the negative spade?
I have wired the positive to the coil and ground the negative. With it wired this way the car won't start. Why?
Now if I start the car and hook the tach up this way it reads correctly.
What am I doing wrong?
- dingo
- IAC Addict!
- Location: oregon - calif
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I'm not sure about VDO, but I'm looking at a Veglia gauge which I use on my Bus. It has 3 terminals labeled: +, -, Ground. Ground goes to Ground, '+' goes to 12V source, '-' goes to the '-' side of the coil (where it receives the pulse, same as the ECU does on F.I.). I'm sure VDO would be the same.
'71 Kombi, 1600 dp
';78 Tranzporter 2L
" Fill what's empty, empty what's full, and scratch where it itches."
';78 Tranzporter 2L
" Fill what's empty, empty what's full, and scratch where it itches."
- Randy in Maine
- IAC Addict!
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- TexasAirCooler
- Getting Hooked!
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- chitwnvw
- Resident Troublemaker
- Location: Chicago.
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When I hook it up this way my bus runs like garbage and the readings are way off, like I am idling at 200 rpms. It's a lot closer when I hook the - on the coil to the positive on the gauge and hook negative on the gauge to ground. But then it won't start hooked up that way. I got this thing off of ebay, I'm starting to feel like I got fleeced.BeetleWarrior wrote:Positive is tach power
Negative is ground
G connects to coil
- TexasAirCooler
- Getting Hooked!
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Humm... According to the wiring diagram the G is suppost to hook up to the negitive side of the coil.
http://jvila.club.fr/vdo_how.html
Hope you get it worked out.
http://jvila.club.fr/vdo_how.html
Hope you get it worked out.
Terry
'65 bus • restore project
"Heroes don't wear capes. They wear dog tags."
'65 bus • restore project
"Heroes don't wear capes. They wear dog tags."
- Amskeptic
- IAC "Help Desk"
- Status: Offline
You might have a short/leak in the windings of the gauge. If "G" to (-) on the coil makes it run poorly, it is acting like a failing condensor. Failing condensors will not let the engine start, but it can run, barely. Do not play with leads in vain hopes of finding the magic elixer. What BeetleWarrior said, or bust.chitwnvw wrote:When I hook it up this way my bus runs like garbage and the readings are way off, like I am idling at 200 rpms. It's a lot closer when I hook the - on the coil to the positive on the gauge and hook negative on the gauge to ground. But then it won't start hooked up that way. I got this thing off of ebay, I'm starting to feel like I got fleeced.BeetleWarrior wrote:Positive is tach power
Negative is ground
G connects to coil
(+) comes from any #15 source at the fuse box directly to the gauge.
(15 means ignition-on power only!)
(-) ground to sheetmetal in area,
(there is a multiple spade ground on fresh air plenum near wiper motor)
(G) good strong fresh wire no sharp edges or nicks in insulation to #1 (-) terminal on coil.
Illumination should have a (+) coming from any instrument illumination source (grey/red wire) and a (-) that is independent of the gauge (-).
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- chitwnvw
- Resident Troublemaker
- Location: Chicago.
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