Is this possible?? please help!!!
 

so i just swapped out my blown r154 for a newer one that i picked up with another gauge cluster. the cluster is out of a 91 and i have an 87. i removed my cluster and put the new one in and double checked that everthing was connected. i fired up my car and nothin on the gauges work except for all the warning lights and such. none of the six gauges work (of coarse not the speedometer cause my cable is broken). I wanted to know if this is supposed to work or not.

any help would be great thank you

The clusters are cross compatible. The only thing you'd ever have trouble with when swapping clusters is that the GE and GTE tachometers are different and require modification.

Have you replaced the 7.5A Dash fuse in the driver's side fuse box? Made sure all of the connectors in the back of the cluster are securely plugged in?

i havent checked the fuse yet but could that really be the problem? and how can i tell the difference between a n/a cluster and a turbo cluster? the only differences between the two are there are more lines in between each indecated line and the redline is 250 rpms lower. but damn i forgot it has a boost gauge so its deffinately from a turbo model. do you know of anyway i can check to make sure the gauges in the cluster actually work?

oh btw thank you

Yes, the one fuse could be the problem... that's why I suggested you check it... :frown:

Yup, the turbo has a boost gauge and the circuit for the tachometer is slightly different. If you were to use a N/A gauge in a turbo you'd need to either swap in a GTE tach or swap out some of the resistors in the GE tach.

The redline difference and the number of lines on the faces is a difference between the pre89 and 89 and newer models of MKIII. The 89 and newer had a heavier crank with more counterweights requiring a lower redline but promising greater longevity. The pre89 crank is lighter, hence the higher redline. The year of the car isn't a dead give away as to which crank is in your car though. The earlier, lightweight crank is the 6M and the heavier is the 7M... they've both been found in '88 and '89 vehicles, but that's the general time of the changeover.

alright so the fuse isnt it because i put the other cluster in and it works just fine so what now??? that info about the crank is helpful :bigthumb:

Time to start tracing the circuit... something's most likely burned out or possibly torn. Also check the sockets where the plugs connect to make sure the soft circuit isn't folded and that the copper contacts are intact.

If it's the same type of cluster as your original (turbo and turbo or n/a and n/a) you could swap all the gauges over to the shell that's functioning properly (You can do it with a GE to GTE or vice versa but you have to cut a trace and add a jumper, IIRC). The only thing which may not have a connection on the back is the cruise control indicator LEDs, but there won't function in a pre89 anyway.

I've repaired the soft circuit on two of these in the past, it's not terrible but you have to take a lot of care to expose the traces without cutting through and then solder in a jumper without burning through.

thank you... would you mind running me through the exact steps because im not exactly sure what youre talking about :eek3:. and if its possible pics would be nice but if its not thats fine

I really don't know how to make it any simpler... take out the cluster and look at the green plastic circuit on the back. There are copper traces laminated into it which weave their way through the circuit.... pick one to start with and follow it until it comes to it's end. While you follow each one look for cuts, deep scratches or burn marks or blistered spots. If all's well there then look at the sockets where the harness plugs plug in. The copper traces are exposed there where the pins of the harness plugs meet them. Look for any that are torn or peeling away from the plastic backing.

If all that fails, you can always pull the gauges and swap them into the other cluster. The only thing that the old cluster housing's (into which you'll be swapping the newer gauges) circuit won't have a connector for is the cruise control LED in the gauge face of the '91 tach. (Actually, there's a spot for it, but there are a couple pieces missing and the '87 wire harness doesn't support it either, so don't even worry about it. Just know that it's not going to work... just the LED that is.)

so i looked at all the wiring and its in incredible condition, in fact it looks brand new. so i dont know what it could be and im really frusterated with it. also i pulled out the other clust and all the laminate circuitry is destroyed around the boost gauge so swapimg out the gauges is outta the question

Okay, a couple questions....

Did the old cluster function properly? If so then I fail to see why swapping the gauges won't work... sure, finding the cause of the burnt laminate is still a definite to-do.

Why are you swapping the clusters anyway? just for asthetics?

Can you post some pics of the back of the old cluster, especially the burnt areas? Pull the boost gauge control module and take photos of the circuit under it too.

You've got a short somewhere and it's probably not in the gauge. Were ALL of the gauges in the old cluster functional? Are they all still functional when you plug it back in?