7 volt regulator diy rebuild for gas/temp gauges ?

[AC439]

I have searched on this subject to no avail, searching here said the phrase "7v" is too short. I did search google based on link to 3geez site to no result either. I doubt if I'm the only one having this problem.

My temp and gas gauges will read off at times. When they start to read off, it happens to both gauges at the same time. Usually is both gauges reading higher then they actually suppose to be. Upon getting into FSM, page 25-50 gauge cluster schematic, there is a 7 volt regulator providing fix voltage to both gauges.

Other searched on internet came up with this issue, but it is on motor bike gauges. I can certainly make a 7v regulator from IC such as 7805 or LM317 etc. I am just wondering if anyone here has done it. The 7v regulator is inside the gauge cluster and I believe it is at the back of the gauge.

thanks,
AC

[conozo]

I've heard of a few people having gauges off, so they just switched gauge clusters. You can easily switch out your odometer into the working cluster so that everything looks the same.

[gp02a0083]

i've made 12V regulators using the 7805 before. Crude but effective, heat generated is usually the issue. Shouldn't be a problem with that stepping down from a 12V feed to a 7V. In my applications i choked it down to 5V and had a decent amount of heat generated. id suggest a heat sink if your going this route. however, its possible to replace the regulator, but i would do this after checking measurements from collector/base/emitter.

[AC439]

Thanks for feedback. I surely know to put a heat sink on the regulator. The only thing I'm not sure is how much space behind the gauge that I have to work on fitting the chip. Or if the regulator is built into the inside of the gauge or not. I would imagine the gauges only draw little current or I may be wrong. I think I have to pull the gauges out and put on my test bench to measure how much current they draw when full scale. Then I can calculate the power dissipation on the regulator chip. But my main concern is if there are enough space inside the cluster to fit in my home brew regulator.

[gp02a0083]

I'll take a look tonight at both carb'd and FI clusters i have and ill post the electrical diagram so that should help a little. it would all depend on where and how you would have to mod it to fit it. I cant imagine the regulator to be small like an smd style, these are 80's tech cars after all.

i'd still checkout the old regulator to make sure that there isnt an underlying issue like a short or ohmic connection in some random spot.

[AC439]

Thanks. I don't think there are any smd parts inside. I think worse case is to mount the regulator externally somewhere and run three wires into the back of the gauge cluster (12v in, GND and 7V out).