Square Body (73-91) Speedometer Question

[CattleAc]

My 2000 ECM puts out 4000 pulses per mile for the speedo.

My 91 electronic speedometer needs 2000 pulses per mile.

My question is...can I compensate for this with the DRACs module????

Say program in 7.17 gear ratio instead of 3.55's????

Thanks, Mike.

[RedHeartbeat]

That can be handled in the tune once you get it done.

[CattleAc]

That can be handled in the tune once you get it done.

Thanks...I'd like a little more info on that.

I'm done with everything except the speedometer.

I talked to the guy that did my tune this morning...and he said he couldn't change the pulses per mile. I understand this because the trans wouldn't shift right.

What would I change in the tune to correct this?

Thanks, Mike.

[HarleyDave]

Please post this info I'm at this point as well and want to use a 91 speedo that I picped up on Ebay.

[pcmcobra]

hmmm another guy on fsc said he just repinned his speedo connector for 91 burb elec speedo and his worked fine.
I've got a couple 91 burb clusters..want to do this also.

[CattleAc]

hmmm another guy on fsc said he just repinned his speedo connector for 91 burb elec speedo and his worked fine.

I'm using the same speedo, (91 Suburban)...Maybe I have wrong info on the pulses per mile on the early style electric speedo heads???

Could someone double check my research???

4000 pulses per mile out of the ECM to the speedo, late model C/K?

2000 pulses per mile out of the DRAC's module to the speedo head, R/V model?

[pcmcobra]

I'll ask the guy, I'm pretty sure he just connected the speedo wire off ecm to his cluster...he has an 87 r10 no drac.afaik.

[CattleAc]

I'll ask the guy, I'm pretty sure he just connected the speedo wire off ecm to his cluster...he has an 87 r10 no drac.afaik.

Thanks alot...I'd appreciate that.

[r6z4o6]

Looks like if you have a DRAC you can make 2000 and feed it to your 91 gauges. Just stash it behind your radio or in the glovebox where it goes and have it for nothing else but the gauges. If you want me to email you the 2meg DRAC2.pdf, its got lots more good info. Or see if you can still find it on the net, its been floating around for a good while. hope this helps.

[CattleAc]

Well my little trauma over ppm's was all for nothing.

I installed my 91 Suburban cluster tonight.

I took the speedometer wire from my 2000 ECM and hooked it to my 91 cluster...no DRAC's...just hooked it up direct.

Works great...dead nuts on...very accurate.

The rest of the gauges work good also...temp, alt, fuel, oil pressure.

The temp reads a little low (190 on the scanner reads about 160-170 on the gauge.)

I'll post some pics of the repinning of the connector and some wiring diagrams on Tues. (Just for future search and reference sake.

Thanks again to all who helped. listless, pcmcobra, RedHeartbeat, thanks.

Mike.