Engine Hour Signal on Regular Truck without EH Output

Moat hour meters are 12V. Just hook it to the ignition switch circuit. Simple.

This is not correct. The engine hour meter does NOT connect to the ignition switch. Turning the ignition switch on but without starting the engine does NOT constitute as running engine hours (what if a person turns on the ignition to listen to the radio for two hours?). On heavy equipment for example there is a dedicated output. Not so on trucks (that is why I am looking for the equivilent).

Whatever. Most trucks have an accessory position for radios. What idiot sits in a truck for two hours to listen to the radio anyway?

The "dedicated" output of an hour meter gets its power from where?

Sorry I'm so dumb.

Dude I don't know why you are being so sarcastic and arrogant about this (not that I care). For your information and education, yes, there is a dedicated engine hour connection in most equipment that has it as OE fitment.

See from this link:

http://www.ehow.com/about_5426362_definition-engine-hour-meter.html

Measuring Actual Run Time

• Most hour meter installations will have the counter activated whenever the ignition is set to on. Since the ignition can be on without the engine running to power accessories or while servicing, this type of installation will sometimes give a false count of actual engine run time. A modern alternative counts engine revolution via a sensor, and only logs time if the engine is actually running.

I understand that there is a dedicated terminal on most modern vehicles.

You can't find it, can you? So, I thought I'd offer a simple alternative, dude.

BTW, dude, this isn't sarcastic, or arrogant. I could demonstrate sarcasm and arrogance, but it'd be wasted on you.

Enjoy!

Run both positive and negative meter wires to the engine compartment. Find a wire powered from the ignition switch using a testing tool or multimeter. Turn the switch on and off while testing to determine a proper wire. Connect the power lead from the hour meter to this wire using a wire tap connector. Place the wires parallel with each other with the hour meter lead on the short side. Press the cover over the connector with your fingers and seat the blade of the connector into the housing with pliers.

Read more: Boat Hour Meter Installation | eHow.com http://www.ehow.com/how_8067288_boat-hour-meter-installation.html#ixzz1NqIL2qzm

I would ask the manufacturer or get the service manual for the engine. On a diesel, there might not be an obvious connection point, depending on the specific control scheme.

Tobugrynbak, I like your logic, if the manufacture doesn't have an access point, I would still tee in another pressure switch dedicated to only the Hr meter. You would have to install a relay for controlling the Hr. meter, but it can be done.

The other option is to tap into the alternators output and get a signal from that. Many commercial truck alternators have a lug or lead connection point that supply's power only when the alternator is turning.

The other option is the earlier mention oil pressure method where you use a common normal y open type pressure switch that closes on a pressure increase to activate the meter. They are typically referred to as a Murphy Switch and com in many different configurations and can be found at most out parts centers for around $10 - $20.

However to be honest I too have seen many factory hour meters on trucks plus farm and construction equipment that are connected directly to the ignition power lead from the key switch and do in fact run whenever the key is in the run position.

I've found most hourmeters connected to the ignition circuit too, mainly because it's easier to do it that way.

I beleive that the OP was looking to use the "engine running" signal for some other purpose hence my suggestion of utilising the oil pressure switch signal.

Toyota uses the oil pressure signal on its H & 2H diesels to operate (in conjuction with other factors) the servo motor on the injector pumps.

I've used this signal to switch in House batteries to the main charging circuit on boats and campers. I've don't use the switch directly to throw a relay/solenoid, I just add a handfull of discrete electronic components to utilise the logic state of the oil pressure switch. Not hard to do if you think right...

We've connected engine hour meters through the alternator circuit on some of our equipment. Engine runs-alternator generates.

I agree with lonster that alternater would give real run time.

Yes, but, in many cases (in my country) the alternators do not have a Tach output (W Terminal) so no such option.

connect to + power out of alternator between regualator and battery and ground to frame.

As Lyn stated, connect it to the ignition switch.

The KISS approach is best for this application.............problem solved.

There seems to be some resistance to a logical approach here.

I'm somewhat bemused by all the "solutions".

Reminds me of the windshield wipers on my '72 Vette.

1. Pull dash switch.

2. That actuates a vacuum motor.

3. Vacuum motor opens wiper door.

4. Mechanical contact on door closes electrical switch mounted on firewall.

5. Switch completes circuit and wipers start.

But then that will only run the hour meter when the wipers are on.

bob c,

You are a card.

I hate to keep drumming on this but for some applications that is not good enough as the data for engine operating hours will be skewed, possibly a lot (depending on how long they leave the ignition on without engine running). But on the other hand, as the hours accumulate, probably the percentage of this would become lower and lower and maybe negligible. So the options by order of priority seem to be:

• Dedicated engine hour output
• Oil switch
• Alternator tach output
• Ignition

Cheers

Years ago - 35 or so, I helped build a system that had a stationary engine running a pump that was started and stopped by an automatic control system. There were concerns about tapping into the auto control system because of warranty. The builder found an hour meter that was powered by the vibration of the engine. He just bolted it to the side of the engine block, installation finished, control system finished! KISS. -- JHF

If you want a true running time of the engine the best way would be to put a oil pressure switch that would close at say 5 to 10 pounds of pressure it would only operate the hour meter when the motor had oil pressure. I would wire the ground from the meter to the switch so that when it closed it would ground through the switch and start counting. By doing it this way you just need to find a 12 volt power source that we be hot at all times therefore if your fuel solenoid vale failed and the engine was running with the key in the off position it would still continue to clock the engine. Hope this helps.