SamGrant951

So my voltage cluster gauge has ALWAYS read low (usually 12 or below) and in trying to correct that have replaced almost everything.

As it sits:
-Battery replaced a few times obviously, this one seems to be working well
-Rebuilt alternator, 130amps - just installed
-Iceshark wiring
-The original 86 cluster read low and swapped in a 88 Turbo S cluster that also reads low.

Prior to changing the alternator Ive swapped in a few Bosch voltage regulators and had the alt tested which it tests fine on the bench. Failed a shops load test so thats why I threw a new one in.

After driving it today for about 20 min I checked it with a voltmeter while the car was showing below 12 on the gauge (below the white line, above the red) and it was ~13.4. Shut the car down and it goes to about ~12. Car has been sitting for months, usually on a trickle charger/batt maintainer though.

Where does the gauge get its reading from? What should I check next?

Thanks!

In good news I got the car to full late offset front with new balljoints, new manual tierods for late offset, new bearings, 17x9's with 255/40's. Car feels great, getting an alignment tomorrow AM.

JohnKoaWood

The gauge can be adjusted by the small potentiometer on the back side of the gauge face.. but you will have to pull the cluster and remove the back with the gauges attached , reconnect them to the harness connectors and fine tune it to match your multi meter readings if it bugs you.. mine reads 16V all the time..but I have been playing with my gauges....

User 41221

13.8V (+/- .5 V) off the battery terminals is what you are looking for. Sounds to me like its a ground issue with the dash panel, start by cleaning all the grounds and see what you've got when you are done. I would think the charging system itself is fine unless you are winding up with a dead battey on a regular basis.

Its been too long, we need to meet up and talk cars over beer! I've been doing a ton of trips to Indy and Cinci (twice a month for the last 6 months) and haven't had a chance to give anyone a call yet... Hopefully next time out!

Regards,

xsboost90

yeah man if your in cincy look me up! I'll be in "indy" the 17-19 at Putnam w/ sammy and some other listers....

SamGrant951

John - thats interesting, didnt know you could adjust them.

Scott, Ive previously checked the grounds chasing this issue but can't hurt to check them again! Definitely has been too long, next time you are in the area and have time drop me a line, we'll go grab a drink.

Mike Murcia

Have you ever had the needles off these gauges, or was that your old cluster?

Josh B

Make sure when you turn the ignition to the number one position that you can see the low voltage warning light come on. If you do not see it and the bulb is burnt out that might be your issue. The bulb is part of the circuit and if is out it can cause issues. Also inspect the circuit traces on the back of the cluster (just pull it out - no need to take the cluster apart). That was my problem - burnt out trace to the low voltage light bulb...

SamGrant951

Thanks Josh, the light does come on. Yours was burnt out due to the trace?

Heya Papa Mike - No needles have been off this one, although thats a good thought regarding the last set. Hows the Kiddo?

CurtP

Had an issue with needles that jumped around, low voltage readings along with dim dash lights. Mine ended up being several wiring problems and corrosion between the ring terminals and the grounding plates. A little time with a 10mm socket and some emery cloth fixed the ground problem. There's what - two ground plates and 3 or 4 wires that attach to them under the dash?

RonD.

Can anyone describe in detail how to adjust the factory gauge? Mine is reading 12.3 ish running w/no accessories. Drops to 12 with brake lights on or headlights on heat etc. Battery tests 12.6 engine off 13.8 engine on 13.6 lights accessories on etc. Can I assume my battery/alt. are good? and problem is with the gauge itself? I've read the factory gauge is notorious for reading incorrect.