Tachometer On A 6.5TD

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ryanruck
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Tachometer On A 6.5TD

Post by ryanruck » Fri Aug 24, 2018 11:12 am

Hey all,
My M998A1 previously had a 6.2 and I was running one of these style tachs I had picked up from TNriverjet on SS a while back:

Image

With the 6.2 I had been getting the signal source off of the oil pump drive.

In June a 6.5TD/4L80 was swapped in and I'm still cleaning up some of the odds and ends. One of those is getting the tach reconnected. Obviously there's no oil pump drive to get a signal off of on the new 6.5TD.

I tried tapping the crank RPM sensor but I'm constantly reading +3k on it however I get movement with the throttle. Hooking the tach to the AC tap on my 200A dual volt alternator pegs it.

Am I doing something wrong or, will this tach just not work with the 6.5TD and I'd need one of the ones with the Cannon plug on the back actually designed to hook to the alternator?

Thanks!

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Re: Tachometer On A 6.5TD

Post by Action » Sun Aug 26, 2018 5:39 am

I always thought that tach was just a generic unit being sold to "make work" in the Humvee.
The unit I have hooks to the alternator via a wiring harness that came with it.
The schematic should be in the TM, but you don't have that tach...

Jason

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Re: Tachometer On A 6.5TD

Post by 86humv » Sun Aug 26, 2018 10:47 am

Tach shown in pic above is the one that goes in the dog house tach .box
86 Hmmwv
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Re: Tachometer On A 6.5TD

Post by ryanruck » Mon Aug 27, 2018 3:37 pm

Action wrote:
Sun Aug 26, 2018 5:39 am
I always thought that tach was just a generic unit being sold to "make work" in the Humvee.
The unit I have hooks to the alternator via a wiring harness that came with it.
The schematic should be in the TM, but you don't have that tach...

Jason
Yeah, I've got the PDF of the install instructions for that one which was why I tried connecting to the AC tap on the alternator's voltage regulator to see if that would give me a usable signal.
86humv wrote:
Sun Aug 26, 2018 10:47 am
Tach shown in pic above is the one that goes in the dog house tach .box
So am I correct in assuming I'm out of luck making this one work and need the windshield mounted one?

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Re: Tachometer On A 6.5TD

Post by ryanruck » Sun Sep 30, 2018 9:28 pm

Update: I've got a Cannon plug/windshield style tach. It's the tach only.

Could someone with the full kit installed please tell me what the ITT/Cannon part number is on the Cannon plug on their harness? Should be on the Cannon plug itself and look something like this:

Image

I'm planning on picking up the Cannon plug needed and making my own harness.


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Re: Tachometer On A 6.5TD

Post by Army Kid » Tue Oct 02, 2018 10:32 pm

I have that same Tach in the pic...military one with hour meter is for the tach drive takeoff on the non turbo. I tried a bunch of options to try to get it working when I installed my turbo motor.....nada. Bought a different aftermarket tach, hooked to the generator , works like a charm!

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Re: Tachometer On A 6.5TD

Post by 86humv » Thu Oct 04, 2018 1:19 pm

Connector is same as on Electric speedo system.
MS 3106R14s-6s
I have take offs in nice condition.
They are the solder type.
$ 27 shipped
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Re: Tachometer On A 6.5TD

Post by ryanruck » Thu Oct 04, 2018 7:30 pm

86humv wrote:
Thu Oct 04, 2018 1:19 pm
Connector is same as on Electric speedo system.
MS 3106R14s-6s
I have take offs in nice condition.
They are the solder type.
$ 27 shipped
Is it? Judging from the pictures of the tach, I thought the tach connector looked similar to the speedo one...

I'll take you up on the offer. Money inbound! Let me know if you don't have my address handy and I'll PM you.

Thanks Greg!

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Re: Tachometer On A 6.5TD

Post by ryanruck » Mon Oct 08, 2018 9:39 pm

I've got my new tach in hand, and I noticed that on the pinout sticker there's no listed pins for internal LED illumination like the electronic speedometer nor is there a removable bulb like my old style tach.

Is the internal LED illumination switched with the power or does this version not have any internal illumination at all?

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Re: Tachometer On A 6.5TD

Post by ryanruck » Tue Oct 09, 2018 7:23 pm

Well, if there is supposed to be a backlight, mine isn't working (though I'm guessing there isn't on this model), otherwise the new tach is working perfect!

https://www.youtube.com/watch?v=rSG5lIYS46A

Thanks again for the Cannon plug Greg! All is right with the world again. :mrgreen:

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Re: Tachometer On A 6.5TD

Post by 86humv » Tue Oct 09, 2018 7:25 pm

Never seen one light up with round plug.
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Re: Tachometer On A 6.5TD

Post by Action » Wed Oct 10, 2018 5:00 am

If the harness doesnt hook to the dash light, then it wont light. Why would they want blackout conditions with a big tach lit up on thd windshield?

Jason

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Re: Tachometer On A 6.5TD

Post by ryanruck » Wed Oct 10, 2018 9:27 am

Action wrote:
Wed Oct 10, 2018 5:00 am
If the harness doesnt hook to the dash light, then it wont light. Why would they want blackout conditions with a big tach lit up on thd windshield?

Jason
Which is why I said I assumed it didn't but, considering not everything .gov/.mil or design engineers do always makes sense and, I have a whopping sample size of one (of unknown history though it shows 0 hours) I figured I'd check out of an abundance of caution and curiosity.

There's no denying it's a bit incongruous that the electronic speedometer of a very similar design and the previous generation of tach would illuminate but this one wouldn't.

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