dash cluster

[1990lumi]

Was there a difference in dash clusters in the 90-94 luminas besides the 2 main ones one being max speed 85 the other 125 with oil temp coolant temp and tach...i am wondering because i had the first dash max speed 85 and swapped to the second style and my speed reads about 5x to fast i replaced because the chip in the old board fried out maybe when it fried it cooked my speed sensor?

[RobertISaar]

there is no direct connection from the speed sensor to the cluster. there is speed sensor to ECM, then the ECM creates a signal for the cluster from that.

[Schurkey]

Was there a difference in dash clusters in the 90-94 luminas besides the 2 main ones one being max speed 85 the other 125 with oil temp coolant temp and tach.

92 has oil pressure gauge, 93 has voltmeter instead. Far as I know, NONE of them had oil temperature gauge.

Floor-shift cluster doesn't have shift indicator.

 

I'd expect other differences as well--for example, the 2.0, 2.5, 3.1, and 3.4 probably have different tach redlines, and some didn't have a tach at all.

[1990lumi]

oil pressure is what i meant and the cluster i have in my car was from another 3.1l lumina

[SweetBee]

Pretty sure my 90 Euro had oil and temp. I know it had boil because the pressure would rise and fall with the engine rpms. It was kinda neat to watch the dash come to life as I would accelerate or decelerate.

 

Fun Lumina fact: 1990 had its own font for the gages and dash controls!

[1990lumi]

so if the 90's did come with the "deluxe" dash then if my speedo is off then it should be the speed sensor sense everything else runs right in my car it shouldnt be the ecm correct?

[RobertISaar]

knowing GM, it could be the cluster itself..... and by that, i mean the speedometer calibration resistor.

[1990lumi]

is the speedometer calibration resistor a regular resistor or is it a chip style

[RobertISaar]

it's a laser-trimmed resistor, if you pull a cluster apart, you'll see a white, ceramic block with black patches on it with 14 pins, that is a network of 6 resistors.

 

if you have a tach cluster, you'll see another for that as well.

Edited July 27, 2014 by RobertISaar

[1990lumi]

so no way to just replace a simple resistor :/

[RobertISaar]

yes, but you need to be able to test the guage against signals of known frequency. i have a bench almost entirely dedicated to this.

[1990lumi]

what exactly would i need to test im pretty good with electrical just never done a cluster before

[RobertISaar]

can you buy/assemble a variable frequency square wave signal generator(and some feedback to know the exact frequency it's operating at)? that would be step #1.

[1990lumi]

by square wave signal generator im guessing you mean something like a 555 chip yea i can get them and have used them before to make red/blue strobes for a friends car

[RobertISaar]

a 555 would work(especially if it were hooked up to a flip-flop to keep the output duty cycle at 50%), but you'll need to be able to constantly monitor its output frequency, calcs will only go so far especially with potentially sloppy tolerances on other components(+/-20% capacitors, for instance).

[1990lumi]

how would i constantly monitor its output frequency when its installed into the dash?

[RobertISaar]

this would all be done on a bench.

 

make up a signal gen

pull cluster, run some test frequencies into it, see how it responds

bypass the laser-cut resistor, put a pot in place of it

adjust pot until the speedo reads what it should for a given test frequency

go through the entire sweep of the guage to make sure it is reacting in a linear fashion(if it isn't, you need to pull the needle, reposition and recalibrate)

 

then the cluster can go back in.

[1990lumi]

how do i know what frequencies to sweep through to know if it responds correctly?

[Schurkey]

my speed reads about 5x to fast

Something is SERIOUSLY wrong with one or more of the parts; or there's an enormous compatibility problem. This isn't a matter of "calibration", it's a matter of totally screwed-up.

[1990lumi]

well the wiring harness is different from my old cluster to the new one i have in it but i redid the harness and double checked it and had a shop check it also its wired correctly and the speedo is the only thing wrong with it everything else works except coolant temp but i dont have a sensor in my car its a switch

[RobertISaar]

how do i know what frequencies to sweep through to know if it responds correctly?

 

knowing that the cluster expects a 4,000 pulse per mile signal for the speedometer signal helps. 4000 pulses in one minute(66.667Hz) is one mile/minute(60MPH)

 

Something is SERIOUSLY wrong with one or more of the parts; or there's an enormous compatibility problem. This isn't a matter of "calibration", it's a matter of totally screwed-up.

 

a lot of the 89-93 GP sport clusters have the issue of the calibration resistor falling apart and causing predictable, but incorrect operation. being of the same era and design, i kind of expect the same problem to be present with the lumina clusters. the wife's 90GP had this pretty bad with her car, 40MPH over the datastream shown up as 120 on the dash. took a while to work everything out, but the calibration resistor has always been the problem in all of them that have been in my hands.

[1990lumi]

im not even going to worry about it anymore i think im going to just cry the day away :/ i looked under my car today and the rust has gotten horrible and im thinking its time she goes to the home to be with its familly