Compatibility of 87-91’ Dash Cluster Between Gas and Diesel

[Zion]

I’m currently looking at options for re-incorporating a functioning tachometer on my 7.3IDI. I was originally entertaining aftermarket kits, but it seems like Craigslist is having a dash parts Renaissance at the moment. Being a gas-to-Diesel swap, my truck is currently equipped with a 5k tach. I’ve seen a few diesel tachs for around $50 and sensors for $80. From what I understand, most instrument panels are plug-and-play as far as swapping OEM gauges are concerned. So that begs the question, will plugging in a 4K tach work? I’m not sure if the wiring harness is an issue, or if it is even economically intelligent to return to a factory tach setup seeing its affinity for not working.
I’ve spent some time in the tech articles, but there is no mention of gas/diesel gauge interchanges. Of those threads detailing aftermarket tachs, all of the posts are fairly old and provide part links that are either dead or have greatly increased in price. I would hope that there would be cheaper tach alternatives, but so far, all my google-fu has taught me is that I need to acquire some Daddy’s Money™ if I want to know my RPMS.

 

[Scotty4]

I bought a tach sensor and plug connector on rockauto for equivalent year tach for my truck when I get around to buying the dakota digital dash one day. I don't have rpms currently. I know that the gassers use a different pickup spot for rpm than the diesel so the wiring connection and tach are different.

A cool option I thought about would be to buy a magnetic pickup with the same threads as our IP cover, and just get a digital readout like we use on our control panels at work. Maybe like $100-200 all said and done, just need one from amazon, automation direct, Woodward, allen bradley, so long as you can set tooth count, then you can mount it where you like.

 

[Zion]

I bought a tach sensor and plug connector on rockauto for equivalent year tach for my truck when I get around to buying the dakota digital dash one day. I don't have rpms currently. I know that the gassers use a different pickup spot for rpm than the diesel so the wiring connection and tach are different.

A cool option I thought about would be to buy a magnetic pickup with the same threads as our IP cover, and just get a digital readout like we use on our control panels at work. Maybe like $100-200 all said and done, just need one from amazon, automation direct, Woodward, allen bradley, so long as you can set tooth count, then you can mount it where you like.

I’ve seen a few different magnetic sensors offered by GM brands or other manufacturers, but it seems that you have to use a die to thread them into the same location. Of those options, I haven’t seen a single one that mentions the ability to calibrate by any means I would have at my disposal. If I do go that route, do the magnetic sensors produce an electromagnetic pulse that could operate a mechanical gauge or would I need to wire it in as an accessory?

 

[Scotty4]

You could do a mechanical gauge, we use tach readouts on the box, or wire it in to a plc. Let me research the gauge option and get back to you.

 

[aggiediesel01]

How much of a swap was your truck? If you put the diesel wiring harnesses in place then you should have most of the factory wiring for the tach. In the diesel harness there are a couple connectors on the passenger side of the truck behind the battery that carry the tack signal, A/C Clutch and the signals, for the FIPL sensor (for auto trucks). If you have or find the harness that runs from there across the front of the motor to the tach and A/C, you could plug it in and install the correct tach and sensor.

 

[Zion]

How much of a swap was your truck? If you put the diesel wiring harnesses in place then you should have most of the factory wiring for the tach. In the diesel harness there are a couple connectors on the passenger side of the truck behind the battery that carry the tack signal, A/C Clutch and the signals, for the FIPL sensor (for auto trucks). If you have or find the harness that runs from there across the front of the motor to the tach and A/C, you could plug it in and install the correct tach and sensor.

I bought the truck post-swap. I’m not too familiar with harnesses, but I am pretty sure it is for the gas. When I replaced The Valley pan, I collected all of the miscellaneous wires that weren’t hooked up to anything. All said and done, almost none of the harness is incorporated into the engine. I could add a photo with a decent view of the harness, but beyond that, I won’t be able to confirm until it gets back from the shop.