//// wiring an hour meter ////

Hi all,

Looking to install an hour meter in my car to determine average speed and for maintenance purposes...

So I don't have to go poking holes and all the wires looking for the correct one , where would I go splicing into so that the hour meter only runs when the engine is on ?.

Thanks

Andrew

Like an hour meter that you install on generators and lawn equipment? Those usually work off pulse to spark plug wires, that kind?

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A solution in search of a problem.
If you must. You can use an app that runs off an OBD2 scanner. Plenty of those around. Your not the first to do this. You can't use anything like a normal gauge or anything with a wire for it as it will only be for a pick up signal for spark. You dont have spark. If you could figure out how to do it by picking up a signal off the 3rd injector or from the tachometer and converting this you could just run a raspberry pi 3 if you know how to write code.

Long story short. Its basically impossible unless you run by obd2 scanner that does this already for diesels. Maybe you can but ita not going to be easy

Mongler what obd scanner logs this ,do you know? I haven't found a way to grab engine hours, yet.

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I should say plenty of them but I know of none for diesels. If you cant obd2 it. It's not going to happen.

My hunch is that scangauge 2 would be able to do it . I can calculate thing and it can to rpms so I'm sure it can be done with some programming if it's not already been done. It is a programmable unit.

Does the engine ECU record how long the engine has been running? Maybe it can be read with VCDS.

Mike_04GolfTDI said:

Does the engine ECU record how long the engine has been running? Maybe it can be read with VCDS.

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no it does not.

That kind of stinks. I change the oil on machines based on engine hours but not a car. Oh well no biggie.

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Because doing do on a car is pointless and this thread is pointless honestly other than to understand why you do not need to do things by hours but by miles. Gas engines you can all day long. the only way i know of doing it on a diesel is to
A: get a pulse signal and do the math with programing from a stand along computer via an injector signal
B: Meter the fuel rate (this is how all the "diesel hour meters" are done on aftermarket crap on ebay and amazon)
C:Calculate it form RPMs and a actual clock from a quartz crystal.
anyone else have an idea, go for it because probably less than 0.01% of cars out there have this built in.
doing maintenance based on hours is dumb. if you park your car idle for an hour every day for work then subtract 1,200 miles from your service interval for every month.

if you all find something then please let me know. it would be useful for some applications where use of the engine does not really change at all on RMPS. like boat build. RV seeker did a boat build with a ALH engine and even he commented on this issue.

My diesel trucks have it. I don't think it's dumb. Diesel trucks idle all day out in the oil patch, all day. The drive from camp is short but the motors are running for 12-20 hours a day. End of thread , thanks

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My boat does it by key power, same as most all the equipment I serviced.

My hour meter is connected to the relay panel; X75 IIRC. That terminal is only powered when the ignition is on. The meter itself, is located in the glove compartment. There is a good place for the ground connection behind the right side plastic panel.

iamatt said:

Like an hour meter that you install on generators and lawn equipment? Those usually work off pulse to spark plug wires, that kind?

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Click to expand...

Yes originally I found that out the hard way ... now my mower has an hour meter!

I did get another one that uses 12v as the start switch to activate the meter .. I got a no noise digital model with 3 counters ( one non resettable cumulative timer, and 2 resettable timers).... not backlit so no glare at night.

Vvt

Mongler98 said:

A solution in search of a problem.
If you must. You can use an app that runs off an OBD2 scanner. Plenty of those around. Your not the first to do this. You can't use anything like a normal gauge or anything with a wire for it as it will only be for a pick up signal for spark. You dont have spark. If you could figure out how to do it by picking up a signal off the 3rd injector or from the tachometer and converting this you could just run a raspberry pi 3 if you know how to write code.

Long story short. Its basically impossible unless you run by obd2 scanner that does this already for diesels. Maybe you can but ita not going to be easy

Click to expand...

I got one that switches on to start counting hours with a 12v signal so all I have to do is find a wire or power source that is 12v when the engine is running.

I wished the scan gauge I have had an hour meter in it ( It is permanently mounted in car as a gauge primarily)

Mongler98 said:

My hunch is that scangauge 2 would be able to do it . I can calculate thing and it can to rpms so I'm sure it can be done with some programming if it's not already been done. It is a programmable unit.

Click to expand...

I have one but it is not a standard gauge and I have no idea how to program it ( the manual calls them x gauges ... the ones you can program).

JB05 said:

My hour meter is connected to the relay panel; X75 IIRC. That terminal is only powered when the ignition is on. The meter itself, is located in the glove compartment. There is a good place for the ground connection behind the right side plastic panel.

Click to expand...

Thanks for the lead .... I'll try to find it.

If all you want is a stop watch. These will be fine. Problem is your engine varies in rpms. Unless the meter runs off the rpms it's pointless. If it comes equipped then yea it's not pointless because that's its function.

Mongler98 said:

If all you want is a stop watch. These will be fine. Problem is your engine varies in rpms. Unless the meter runs off the rpms it's pointless. If it comes equipped then yea it's not pointless because that's its function.

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It is an hour meter, not a cumulative rev counter, right?

Every marine diesel I've seen has an hour meter; they are an extremely common item.
https://www.amazon.ca/Qiorange-Tractor-Diesel-Outboard-Rectangular/dp/B01JIHHHME/
https://www.defender.com/pdf/VDO_Viewline_hourmeters.pdf
https://www.defender.com/pdf/VDO_Viewline_hourmeters_install.pdf

If the 12v 'cigarette lighter' outlet in the car only has power when the key is 'on' that would be a simple line to find and tap into.

Hour meters do count all the time that the 'key' or on/off switch has the 12v power connected, so the few seconds most of us have the key in the 'Acc' position would count as engine run time.

Terminal stud labeled 75x, under the dash, power when key is on. As posted above.

Hour meters are common on diesel engine applications where RPMs are generally constant and a good indicator of engine usage... gensets, farm equipment, etc. Not as common on passenger vehicles.

That said, lots of 12V-activated versions on Amazon.

JB05 said:

My hour meter is connected to the relay panel; X75 IIRC. That terminal is only powered when the ignition is on. The meter itself, is located in the glove compartment. There is a good place for the ground connection behind the right side plastic panel.

Click to expand...

Hi

Update: I finally got my hour meter installed yesterday using the x75 terminal for switched power ( thanks for the tip!)...

Question tho ... I plan on needing to use more switched power inside the car .. not high amounts of power but power nonetheless .... how many amps can you pull from that circuit without issue?

Also, there are not alot of grounding locations under the dash so I ended up grounding to the lower nut holding the accelerator pedal.... I'm not overly happy with that location because it runs my wire close to the u joint in the steering column, the clutch pedal and accelerator pedal...I saw the suggestion for a ground but was not able to find it.

Thanks

Andrew

Run an 8 wire for both the ground and the positive on the battery though the gromet on the firewall into behind the dash someplace easy to get tim I chose behind the camera of the dash under the HVAC controls. Use 30/40 amp relays for whatever you want to operate and switch them via the ignition. Running a wire is a task so might as well run one to handle anything. I would get K type wire as its flexible and easy to work with and usually has a thick outer jacket. Dont solder anything, use crimp connections with antioxidant. Most builders advise against solder as vibrations have been known to brake them apart even if done properly as the heat can damage the wire and the jacket. Shrink wrap all connections and work tidy. Not a lot of room to work with. Dont forget a main fuse at the battery for this run. Do the fuse in 8 gauge terminal fuse as well and put an appropriate fuse on each device at the relays.

Under the right side cover of the dash is a good metal chassis to attach a short ground wire. Just pull the cover off; its clipped on.
I do have other wires attached to the x75 terminal such as my 1000 watt inverter for one.
No problem with over amperage.

Best electrical upgrade is "the big 3" all 3 ground points upgraded. If you pull too much you start having issues with lights, charging, and audio issues.

Andyinchville1 said:

Question tho ... I plan on needing to use more switched power inside the car .. not high amounts of power but power nonetheless .... how many amps can you pull from that circuit without issue?

Click to expand...

Rather than trying to not overload that circuit, you'd probably be better off running a larger line direct from the battery (through a suitably-sized fuse, of course) into the cabin, then using relays triggered off that switched circuit to disperse power from there to wherever it is you want to send more switched power.