factory tach with 5.3

[XwalkerX]

so i have a tach dash in my 72 c10 that im trying to get to work with the l33 swap. i purchased the dakota digital SGI-8E tach converter since i understand that the tach output from the harness is equivalent to a 4cyl setup.

pic for reference



i ran power and ground to the box.

i ran ground to the tach, the tach power wire i have going to the "normal" port set to 8cyl and also bridged it to the power thats going to the box.

for the "signal in" wire i spliced into the white wire at pin 10 and made sure it was set to 4cyl.

ive tried both the hi and lo voltage positions but still get no movement on the tach.


can anyone give me some insight if im doing something incorrect?


and of course a pic of the truck

[LockDoc]

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I don't know what an l33 is or what ECM/PCM it uses but on my '67 with a stock tach dash & LS1 with the 411 PCM I just hooked the tach wire from the PCM to the tach output post on the back of the tach and changed the PCM resolution from 6 to 3. Seems to work OK....

Here is what lsnova said in another post:

Depends on what year your PCM is, but generally the 2003 and newer will need the pull up resistor. Also you'll have to change the tach resolution from 6 to 3 in the tune to make it read correctly since LS motors use a 4 cylinder signal, otherwise it will read half of what it's running (on a V8 tach). Other than that, just hook up the ignition wire like it was originally and hook the signal wire, the one that went to the coil, to the tach output out of the PCM, generally a white wire at C2 10, but that may depend on year and application.

LockDoc

[XwalkerX]

L33 is just the engine code for the HO 5.3L.

Also I'm an idiot and I figured it out. I was running a tach wire to ground when the tach is already grounded in the cluster.

Everything works as it should.
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[1972k10shortbed]

Originally Posted by XwalkerX

L33 is just the engine code for the HO 5.3L.

Also I'm an idiot and I figured it out. I was running a tach wire to ground when the tach is already grounded in the cluster.

Everything works as it should.
Posted via Mobile Device

I have tried to hook my tach up with my 5.3 and also my stock 350 truck. Neither one worked. Ive never hooked one up properly before. Any help would be appreciated.
Thanks

[BR3W CITY]

Would you elaborate as to the actual function of the box? I'm not using a 72 tach, so is the problem an issue of pulse signal?

For me, running an aftermarket electronic tach, a pullup resistor and the regular tach output was all that was needed (running on 4cyl mode). I'm wondering what the box does that a .30c resistor doesn't?

[foamypirate]

Originally Posted by BR3W CITY

Would you elaborate as to the actual function of the box? I'm not using a 72 tach, so is the problem an issue of pulse signal?

For me, running an aftermarket electronic tach, a pullup resistor and the regular tach output was all that was needed (running on 4cyl mode). I'm wondering what the box does that a .30c resistor doesn't?

I would assume it's used to allow a factory tach to operate correctly, though it sounds like changing something in the tune can also allow this.

[XwalkerX]

the box essentially allows you to run factory gauges but yes there is also the route to changing it to an 8cyl output in the tune. i dont have someone readily available to adjust my tune so im ok with buying the box.

also in an aftermarket tach you wouldnt need something like this because you can typically change the tach input to read in 4cyl mode then just add a resistor to beef up the pulse signal strength.

[aknovaman]

I have used these for years and are half the price. I use them when swapping in a v8 into a chassis that originally came with a v6.

http://www.bakerelectronix.com/products_tsd/

I use them when converting from obd2 to a obd1 PCM in the 96 Impala SS so the dash reads the correct RPM.

[68c10airstream]

Terry at lonestar dyno straightened my factory tach issues with my 2001 5.3 ls. I replaced the 5,000 rpm tach, installed the 8,000 rpm tach and sent my 411 pcm to terry. He changed the settings and if i remember correctly he said you can scale the tach signal to be a higher voltage so you don't need a pull-up resistor. He fixed this along with a few other things and worked perfectly upon install. His avatar is "CRITTER".