Tach Wire?

[TNRGreene]

I need to find this wire to connect to. Insructions say:
TACH input is designed to work with most Tachometer signals (down to 3 Volts), without the need for a separate adapter. It can be connected to a tach signal, coil trigger signal, or fuel injector. DO NOT connect it to a high voltage wire.

Any Ideas?

 

[Lennart]

What vehicle?

 

[TNRGreene]

04.5 K2500 GMC DMax

 

[Cobra#3747]

generally diesel tachs run off the alternator if I am not mistaken.

 

[LarryJewell]

what are you hooking up

 

[LB7Diesel]

generally diesel tachs run off the alternator if I am not mistaken.

That's what I was told also.

 

[JoshH]

Bump. I'm wondering if anyone knows where which wire may work for this. The instructions I've read say the same thing as what Todd posted.

 

[LBZ]

When I hooked up my water meth system, to read duty cycle they had me tie right into one of the injector wires in the main harness to the injectors. The voltage there may be too high for a tach signal though........

 

[McRat]

There is a tach wire at the bale connector, IIRC, it's white.

I posted the pin-outs for the bale connectors somewhere.

IIRC, it's a "double fire" signal. This means it's one pulse per rev, not one per cycle. This is like LS1 engines? Normally tachs have a switch for this.

I was running a digital window switch for nitrous, and this is where I tapped into.

 

[JoshH]

There is a tach wire at the bale connector, IIRC, it's white.

I posted the pin-outs for the bale connectors somewhere.

IIRC, it's a "double fire" signal. This means it's one pulse per rev, not one per cycle. This is like LS1 engines? Normally tachs have a switch for this.

I was running a digital window switch for nitrous, and this is where I tapped into.

I'll see what I can find. Thanks for the info, Pat.

 

[McRat]

I'll try to hunt down the pin-out today and post it here.

 

[Kat]

I'll try to hunt down the pin-out today and post it here.

Here is the thread for the LLY



http://www.duramaxdiesels.com/forum/showthread.php?t=3984&highlight=bale

 

[JoshH]

Here is the thread for the LLY



http://www.duramaxdiesels.com/forum/showthread.php?t=3984&highlight=bale

I found that one last night. I thought there was a pinout for the LBZ bale connectors somewhere, but I can't find it anywhere. Anyway, I need it for an LMM if anyone has it.

 

[McRat]

I really need to take better notes.

I'm starting to think I used an ECM wire, not a bale wire.

But you can probably use the crank or cam sensor wire for a pulse, these are in the bale.

Problem with using an injector is the multi-pulse feature of our diesels. Not sure if that would do the trick.

I do know that the window switch worked on Casper, and I didn't use an injector wire. 99% sure it was noted as TACH, and it was ECM.

 

[Cougar281]

FWIW, there's nothing labeled 'tach' on the pinouts for the ECM. Not sure how or why there would be a tach signal anywhere, except maybe for the FICM, but even then, that has hish speed CAN to communicate with the ECM, and the cluster gets its signal via class2. A full text search of Mitchell only found one instance in the electrical section, and that was the 'tachometer' label in the cluster diagram.

You can't just tap the crank or cam sensor signals. They're alternating current, not DC pulse.

I suspect the tach signal is generated in the ECM using the crank sensor signal, and near as I can tell from the diagrams, never shows up as a descrete wire.

 

[McRat]

For the LiLLY, it's on the ECM. I brought it to the top.

White wire, pin 37 on the C3 grey? connector. Called Engine Speed Signal, not tach.

Guess my memory ain't getting better with age.

For LBZ, need the pinout for the ECM, look for Engine Speed Signal. I believe the ABS and trans needs it.

 

[darkness]

IIRC, it's a "double fire" signal. This means it's one pulse per rev, not one per cycle. This is like LS1 engines? Normally tachs have a switch for this.

IIRC you had to set the tach on the LS1 to run on the 4 cyl. pulse? been 9 years since i installed a tach on an LS1

 

[x MadMAX DIESEL]

Anyone wire up a gauge lately? I'm trying to figure out this spek gauge. I've got the engine speed signal tapped and using a phone charger to get me 5 volts (got to be 3-12) for calibrating the tach. Someone said you need to bring the signal wire down to a 5 volt which according to the instructions that's not right. But the labeling in the instructions does not match up. Like a purple wire isn't even pinned up right from the factory according to the pin out in the instructions

 

[JoshH]

Looking at a pinout diagram for an LB7 ECM, I see pin 10 in the C2 ECM connector is a white wire labeled engine speed signal. Anyone know what kind of signal this puts out and if it is sufficient to drive a tach? I don't want to experiment with it and risk frying the thing.

 

[Stingpuller]

Tach

It is the white wire. You also need to run a hot (12 volt) wire with a resister to get that same 12 volt wire down to 5 volts. Hook the 5 volt wire up to the tach signal wire from ecm and set your tach on 4 cyl.