Low-Reading Gauges - Rallye Pac

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jae

Master Mechanic
Oct 11, 2006
460
2
16
It's been a while since I've posted and am hoping you guys can help.

I have the rally gauges (volts, temp, fuel, oil) on my 86 Cutlass and just like my on 81 Salon they are reading low. I do not believe it's a battery issue as the battery/charging system is 12.5V engine off and 14.35V while running - I did a quick & dirty battery/charging voltage test. I'm thinking it may be more of a grounding issue but before I start chasing grounds/pulling wires, ripping the dash apart and the like I was wondering if anyone here had the same issues and what were your fixes to have the gauges read more accurately?

I went through this on the 81 (wish I still had it) and really don't want to live with it with the 86.

JAE

New Info:

Over the weekend was wrenching on the Cutty and it seems this time just the volt gauge was acting goofy. It was reading about 9 ~ 10V, but voltage at the battery was 13.88V at the battery, 13.90V at the alt at warm idle, slightly higher at cold idle.

I have an aux coolant temp gauge and that & the in-dash gauge were reading pretty close. The oil pressure seems to be reading ok and fuel is a guess but believe it's pretty close. Again, goofy as the last time I was working on it all were running low. Any thoughts from the board?
 
Sep 1, 2006
6,687
31
0
Tampa Bay Area
Have you tried testing the plugs they slide in to? See if the voltage is correct there first as it may be just a case of dirty contacts, or the cluster may be a little loose after all these years. Tighten it up or try pushing in on the cluster with the car running and see if the readings change. Remember that GM did not use a positive locking plug to connect the cluster to the harness.Try the simple stuff first before ripping it all apart. I am dealing with the same problems as I swapped the dash harness to one with the Rallye Pack gauges and also swapped the engine harness to one form a GP with a 305 and gauges, but no tach. I just got the tach and the oil pressure gauge to work so far, but I found that the connections in the back don't like to connect well sometimes.
 

jae

Master Mechanic
Oct 11, 2006
460
2
16
Thanks for the info.

I didn't have a chance to try anything this past weekend, too much to do around the house!!

Did you have any problems / issues removing the old instrumentation / cluster? I looked up info on that on a couple other sites and on site stated exactly how to remove the cluster but the only problem was the trim panels. One site stated there were spring clips holding the trim panels / vents in place but didn't state how to remove them. Any suggestions? Don't want to break them as they are in really good shape.

JAE
 

cles

n00b
May 10, 2007
1
0
0
I also have gauge reading problems since I swapped my 88 cutlass over to the rally pack. The volts and gas read low. The temp reads high. Am I'm guessing the oil reads low also. Sometimes the gauges have no reading at all...volts are at zero, temp is pinned to the right, gas reads zero, and the oil reads zero (that's why I'm guessing it reads low). Seems to me like a bad ground, but the gauge worked properly on the old cluster.

I was going to connect both ground wires together to see if that would help. Has anyone tried this after the conversion??

The trim and vent panels just pull out of the dash. They can be very stubborn and hard on the fingertips....they'll either come off, or they will break.
 
Sep 1, 2006
6,687
31
0
Tampa Bay Area
To remove the woodgrain, you will need to pull them out by hand. The far edges by the vents do not have clips, pull there and you risk breakage. Instead pull on the center of the one in the middle of the dash, and from the inner edge of the vent to the inner edge of the trim panel on the one by the headlight switch. Removing the outer cowling around the gauges comes next. There are 2 sizes of bolts used to hold it and the gauges together. IIRC, one is 1/4 in the other is something like 3/32. Oh, and the gauge cluster is held in by 4 1/4 in screws, the smaller ones disassemble the cluster.
 
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