This is not exactly the kind of swap you guys may like to see but I need a little help concerning the reluctor wheel on a 12v cummins swapped 2002 Suburban 2500. I bought a 24x reluctor wheel and have started modifying it to use on my Cummins balancers. I notice it has balancing holes cut all in it and it is heavily weighted on one side for the LS applications but I think this may cause some vibrations on my Cummins setup. The reason I think this is when I chucked the reluctor into my lathe is was clearly out of balance even causing this 2000lb lathe to have light vibrations at higher speed. My question really has to do with the possibility of making my own reluctor wheel, I noticed this factory unit has two sides, does the CPS read both sides at the same time? I was hoping I could create a simple single 24x reluctor wheel maybe scaling it up to where it would fit this cummins balancer better as the LS unit is a bit smaller than I would like. Any help with this would be great. I found this drawing of a 24x reluctor but would this satisfy the crank sensor to give me an accurate tach signal? I left the 6.0LS ECU and all that in place so I can use the the factory cluster and my goal is to just get a tach signal.



Thanks
Mike

Here is a little test drive video of my Cummins swapped Suburban for those that are into this kind of swap.

 

To get things going for now I just machined some steel bar to a nice press fit into all the reluctor wheel lighting holes. The reluctor is not perfectly balanced but much better now. I would still like to hear about the possibility of making my own larger diameter reluctor or possible just matching the cummins balancer to create the tone signal needed to operate the tach.

 

That’s a cool swap. What was the reasoning behind it? What’s your fuel mileage vs stock?

 

Why do you need the 24x wheel? Just for a tach? There has to be an easier way

 

I just like doing Cummins conversions and other engine swaps. Not many suburbans with a cummins and for sure not many with an NV4500 as well. The suburban was purchased without engine or transmission as someone has pulled the 6.0 and 4L80 for some other kind of swap.

The Suburban cluster is difficult to satisfy and most folks just end up putting autometer or some other gauge in the dash. I want to use the factory cluster and to get the tach to work you have to present the 24x signal to the ECU so it will then send the info to the tach on the cluster. NO tach helper or anything like that for GM products.

 

I like the swap idea. I have a 97 dually that would be great to put a Cummins in but I’ll never actually do it.
The tach on the cluster is a 12v square wave, I’m quite confident though haven’t done it, you could find something that reads rpm from the Cummins and will output a 4cyl 12v square wave, completely bypassing the stock ecu. The temp, volts, and maybe speed go over vpw but the tach doesn’t.

 

I did a crude test spinning the reluctor wheel with a drill to verify the rotational direction before installing it on the balancer. I was not able to get any kind of tach movement no matter what I did. I figured I would have got the tach to at least bounce to show that some signal is being received but not even the slightest movement has me a little concerned this may not work. I will look into the 12v square wave signal that you are talking about and see what I can figure out.

 

Gmikehall,
thanks for the feedback

 

this. if you have access to a silly-scope (oscilloscope), it would be good to look at the crank sensor output from and LS, and then at the ECU tach output simultaneously. they are vastly different signals. I believe on the LS, the ECU tach OUTPUT is pulled up to 12V, and the ECU grounds it to create a square wave. not sure on the frequency or duty cycle but if you able to look at a friend's vehicle with a running LS, shouldn't be too hard to figure out.

 

I have a major update on the Tach issue. I believe the sensor I have was not correct. I ordered all the sensors off amazon I needed and didnt really verify any of them just assuming they were correct. Well after struggling to figure out why there was no tach signal not even the slightest I started my research on possible problems. I came across someone changing a sensor and notice it didnt look like the one I have here. So turns out this sensor is for older GM engines not the LS based engines which is the 24x signal. Going to get the correct sensor, rebuild the sensor mounting bracket and hope my tach will be operational..

Here is what I had done so far, of course the sensor mount will need rebuilding to fit the totally different LS sensor.

 

I'll bet you could make something on Send cut Send to have an upsized ring. Cool project! If you weren't using the manual transmission, that reluctor ring would be necessary to control the 4L80e trans.

 

I have the tach working now with the correct sensor. I am going to totally rebuild the sensor mount but I hacked it together just to verify that it would work. What is nuts is this bone stock 12v Cummins tops out about 2500 RPM...haha

Yeah I thought about using a 4L80 but didnt want to deal with the tuning or transmission controls and then on top of that a mild 12v would destroy a 4L80 without a proper build. I do have a low stall triple disk TQ and billet flywheel for a cummins/4l80 but I chose to just use a NV4500 for this particular project.

 

I have my cluster working pretty well now with some minor mods. I am looking into finding an Arduino design that I can use to turn the Transmission temp gauge into a boost gauge and then I will print a custom factory(ish) looking gauge face. I love making things look factory as possible. I covered the shifter indicator text screen with aluminum foil tape and it does a great job of hiding that no longer needed information from the cluster. Just need to figure out why my ABS light is on and maybe then I can get the cruise control to work as well. Starting to get all the little details worked out slowly but surely.

I do have an issue that I have been having trouble on. The fuel gauge is intermittently working but when it does work the gauge is clearly not correct. The fuel tank is virtually full yet when the gauges does work it only reads about 1/3 tank. This is a 2500 suburban so it did have dual tanks with dual sending units. I checked the main tanks sending unit and it has the correct 40-250 ohm scale so apparently these suburbans had a gauge that utilized a different scale or something? My idea is that they had the two fuel level sending units in series and therefore the total sum of the ohms would dictate the fuel gauge level. I may be totally off on this and that Is why I am asking on here. I know this is not LS related but maybe someone here would have more knowledge of this issue I am having. I think possible the intermentant gauge issue is a ground possibly and I will address that once I starter finalizing the harness which currently is a rats nest.

https://www.youtube.com/watch?v=q2wV...ature=youtu.be

 

Suburbans only came with one large tank. Only pickups had 2 tanks. Do you have 2 filler necks?

 

The 2500 suburbans had dual tanks but it was a complexe setup using the rear tank as a header to supply fuel the main tank as fuel was used up. It was going to be too complicated to make that system work and 26 gallons of main tank is fine for a cummins swap anyhow. The 1500 suburbans did only have a single tank setup but not the 2500 versions.