Another Adding tach

[green55]

will the Lmc tach conversion kit work on an 89 Jimmy with TBI without too many modifications?

I know this general question is asked a lot, I’ve read a bunch of old threads about it. I’ve seen that 90-91 have an electric Speedo that can make things difficult. Seems like TBI could also be a factor? But as my Jimmy is right on the borderline year-wise, I wanted to ask.

I’m not great with electrical stuff…doesn’t mean I couldn’t figure it out but not trying to destroy my existing cluster in the process.

looking at their site, they have one for 83-87 that says “models with TBI will need to modify the tach feed wire connector”.

Tachometer Conversion Kits

Explore our tachometer conversion kits for Chevrolet Blazer, GMC Jimmy and Chevrolet/GMC Suburban 1973-91. Ideal for revamping and personalizing.

www.lmctruck.com

It certainly isn’t cheap, but finally getting towards the end of my list of mechanical repairs and moving on the the interior soon. Tach or a new dash are probably the first things inside

 

[Cucv_M1008]

I just ran a tach off the coil and power and ground and it worked on my 88 tbi rig

 

[ZooMad75]

The issue with the 90-91 electric speedo clusters and a conversion like that is there is no place to put the small fuel gauge. On those clusters there are two partitions cast into the housing in the hole where the small fuel gauge or clock would go. So one would have to cut them out to fit one in.

If yours is a mechanical speedo, you should have an open hole in that corner unless you have a clock. Should be fine.

 

[kennyw]

The factory TBI tach output is a loose connector next to the distributor vs connecting directly to the HEI distributor cap on a carb motor. Other than that, not much difference in how you would install that kit.

 

[dyeager535]

will the Lmc tach conversion kit work on an 89 Jimmy with TBI without too many modifications?

I know this general question is asked a lot, I’ve read a bunch of old threads about it. I’ve seen that 90-91 have an electric Speedo that can make things difficult. Seems like TBI could also be a factor? But as my Jimmy is right on the borderline year-wise, I wanted to ask.

I’m not great with electrical stuff…doesn’t mean I couldn’t figure it out but not trying to destroy my existing cluster in the process.

looking at their site, they have one for 83-87 that says “models with TBI will need to modify the tach feed wire connector”.

Tachometer Conversion Kits

Explore our tachometer conversion kits for Chevrolet Blazer, GMC Jimmy and Chevrolet/GMC Suburban 1973-91. Ideal for revamping and personalizing.

www.lmctruck.com

It certainly isn’t cheap, but finally getting towards the end of my list of mechanical repairs and moving on the the interior soon. Tach or a new dash are probably the first things inside

I suspect one reason for the difference is the alternator used. As mentioned the lower left position on the late clusters isn't cast for a gauge at all. It's setup for indicator lights, one of which (in some applications) is the alternator charge light which is necessary for the CS-series alternators to work properly.

No clue if the CS-series started in 1990, or earlier. If it started earlier, then perhaps the cluster housing changed whenever that alternator went into use.

Not spending a bunch of time thinking about it, you could probably use any cluster housing from 1981 to '87 or so if yours isn't cast for the small fuel gauge, and just swap everything over.

The wiring pinout/flexible circuit changed for at least the 1990+, but I don't know if 1989-down are all the same, or if there were other changes in the 1981-1989 range regarding wiring, assuming the same cluster layout (gauges, not lights).

 

[green55]

Thanks y'all. This is helpful and makes me hopeful.

I do have the empty gauge spot where the clock goes, at least it looks like it from the outside. Has the black background with white circle. Haven't taken the cluster apart enough to determine if there's actually a hole in the plastic backing to mount a new gauge to, but I think that kit comes with a new plastic backing anyways.

I imagine I can lookup on youtube putting any tach onto a 87-90s GM TBI and it'll be the same wiring needed. Then it'd just be installing the gauge into the cluster correctly, which I think that kit comes with pretty much everything new except swapping over all of my existing gauges

 

[82355]

I did it to a'90.

Martin

 

[obijuank5]

What I did to hook the fuel gauge to the printed circuit on my big truck tach fuel combo gauge.



View attachment Snapchat-447493972.mp4

 

[Gibby56]

I’m not sure if this guy is still around but i think i have one of his units in my cluster for my 90 K5. Works great and super simple to wire. Pulls power and ground off the printed circuit and has a single input wire that plugged into a factory connector by the coil for the TBI setup.

Chevy Truck Impala Oldsmobile Nova Tachometer Repair Restoration

my cluster