1990-91 K5 blazer NP241 electronic speedo swap question

[7387chevynut]

Hi Guys,


I recently bought a 90 K5 blazer, the previous owner installed a NP208 out of a 86, because the person he bought from ran the k5 down the expressway in the winter time over 45mph and blew the Np241. but now the speedometer doesnt work.........for the obvious reason stated above.

Now I know the 90 model year K5's had the electronic speedo, and I have been trying to find a 241 from either 90 or 91 to put back in it..........but as usuall I cant find what i need, when I am looking for it.

BUT..........I was wondering.............couldnt I just swap out the 1990 instrument cluster and install a (1989 model year one from a K5 that I have) and install a new manual speedo cable...........and problem is solved?? I dont see how it wouldnt work...........but figured to ask anybody else who might have done this.

 

[Russell]

If you were up to changing the pin out of the instrument cluster connector, installing a resistor for the alternator to replace the warning light, and loose the check engine light then yup, you can install an older cluster no problem.

I'd just find the proper transfer case though, shouldn't be impossible to find one...

 

[4X4HIGH]

You can easily swap in the 89 cluster and add the speedo cable and then hook up the optic eye so the cruise control and the ECM get the correct info they need. I just recently went the opposite way and went from mechanical speedo to electric and converted to the DRAC system instead of the optic eye.

 

[6.5L]

6.5L from 1994 going into 1987 crew cab chevy

You can easily swap in the 89 cluster and add the speedo cable and then hook up the optic eye so the cruise control and the ECM get the correct info they need. I just recently went the opposite way and went from mechanical speedo to electric and converted to the DRAC system instead of the optic eye.

I am new to this site. I read comments you made concerning changing from electronic to mechanical speedo on gm K5. Here is my project. I am installing a 1993 6.5L with turbo into a 1987 crew cab 2wd. I will be using the 1994 5 speed NV4500. The trans now has the electronic sensor. I have a 1990 K5 on the lift. I just sold the transfer case and noticed that it used the electronic speedo sensor. I may try to use the instruments or just the speedo gauge from the 1990 K5 installed into the 1987 crew cab. Will I have to use any of the computer and harness from the 1990 K5 or is this some thing that I can hard wire. The 1987 crew cab originally had a 454 in it. The 6.5L actually came from a 1994 with the previous owner replacing the electronic injection pump with a 1993 mechanical pump. My other option is to find a mechanical drive to fit the nv4500 5 speed and use the existing 1987 cable driven speedo. The 6.5L is now setting in the rolling chassis of the 1987 crew cab. Raised the motor mounts up 5/8 inch to get some clearance for the rh manifold bolts located just under the turbo. The crossover pipe will need just a little alteration since it is tight against the lh frame rail. I will need to trailer the frame with engine installed to an exhaust shop to get a custom exhaust pipe to run from the turbo outlet down into the area between the rh frame and side of the transmission. The frame of the 1987 is much more narrow that the frame of the 1994, thus the need for the custom pipe. I have been driving a similar truck for the past 30 years. It is a 6.2L diesel in a 1983 crew cab. I purchased that truck new and after 30 years I am still running it on its original engine. Just tired of living with 130 HP on the 6.2L that is why I am fitting the 6.5L into the 1987. I will also need to replace the A/C heater assy on the 1987 with a non A/C unit since the turbo on the 6.5L creates an interference problem with the A/C evaporator. Good thing I own a salvage yard, it makes obtaining extra parts a lot easier.
Any assistance you can provide is greatly appreciated. Any additional sites that you suggest visiting also will be appreciated.

 

[Russell]

You'll need the 90/91 instrument cluster and a DRAC. You can easily make your own harness. Just run two wires from the transfer case up to the DRAC (make sure you twist them together for electrical noise cancelling), provide power and ground to the DRAC and run the speedometer signal out to the new cluster.

 

[4X4HIGH]

You'll need the 90/91 instrument cluster and a DRAC. You can easily make your own harness. Just run two wires from the transfer case up to the DRAC (make sure you twist them together for electrical noise cancelling), provide power and ground to the DRAC and run the speedometer signal out to the new cluster.

Russell got it right.