Mopar Muscle Association UK

hi all,would like some help with this please,the brake lights stopped working a while ago,checked all the bulbs and bulb holders,all good,found out it was the 20 amp fuse had blown,cleaned the fuse box and replaced all the fuses,got all the rear lights to work,held the brake pedal down with a piece of wood,ran the engine for twenty minutes,all the fuses were cold,every thing worked ok,i had to replace the battery after that,as it was on the way out,had been on the car for around 10 years,the engine turns over now as it should,but ive put the meter on the battery,and its putting more charge in now,than it was before,i thought i may have created a spike,so i have changed the voltage regulater,but the readings are the same.i havent done the bulk head conversion,but i did the same as matt h did,have by passed the amp meter,up untill now,every thing was ok.have earthed the regulater,and have allready done the other earths.the readings of the battery are,on tick over are 14,v .rev the engine and it goes to 14.50 v .on tick over with the lights on it goes to 12.50 v .the battery i changed is the same as the old one,i have got a spare alternator,which i will fit to see if this makes any difference.but are these battery readings to high?or is it just me worring about it.thanks

Should see a max of 14.6V, but if you have the old school mechanical regulators as originally fitted to '68's, they can "spike" above that and cause issues, especially with electronic ignition.....

Thanks for the reply Pete,I did have a electronic voltage regulator on there for a long while, but I had a spare one with the points, which I fitted, that could be the problem I have? Have bought another electronic one, should receive it tomorrow,I did take the cover of the old electronic one, and there was a bit of rust in it, where the water had got into it

I'm not an expert on automotive electrics but I've gained quite a bit of experience over the years especially with my 70 Challenger that had a difficult to diagnose short for many years which I finally resolved last summer. Given that I constantly had to disconnect my battery anytime I parked lest I return to have a flat battery, I was always checking the charging voltage to ensure the batter was charging properly. And Pete is right on the mark, 14.6 is your upper limit; a proper charging circuit should be between 13.5v and the upper limit, so your alternator is definitely not overcharging, if anything, it's undercharging under load as 12.5v is low. Does it remain below 13v with the lights on when the revving the engine?

Electronic ignition - electronic voltage regulator. You are electronic ignition ?

I went through a phase of blowing voltage regulators because of dodgy alternator.
I'd suggest if you have cleaned it all up and brakelight work without getting warm, your numbers sound OK to me.


Do the ammeter bypass though and pop some fuses/fusible links in. Threads everywhere on it. Search 'madelectrical'.

thanks again for the reply,s .will check the charging again,overe the weekend,yes its got a electronic ignition,msd,thanks

Did you find out why the 20 Amp fuse blow?

As there may be something there that caused it to blow.

I did think about,why the fuse had blown, I've checked all the rear light bulb holders,there ok, going to check the brake light switch on the brake pedal, and I'm going to have a look at the bulkhead connections as well, will be fitting the new electronic voltage regulator over the weekend,I did fit a battery cut off switch a while ago, goes on the negative side of the battery, I've just found out that they can create a bad earth,so the alternator would be putting in more of a charge, hopefully I'll get it sorted out soon, thanks for the reply

Hi all, forgot to post back, regarding the overcharging,I replaced the electronic voltage regulator, cleaned all the earth's up in the engine bay, added a earth lead from the alternator to the inner wing,and all is good now, not sure if it was the regulater,or a bad earth, but I think it may have been that the voltage regulator,as there had been a trace of water inside it, thanks again for all the replys,

Glad you got it sorted!

Well done. Gremlins in that little setup can drive you nuts - other times they run for decades !?!

three counties wrote: ↑Thu Apr 29, 21 6:12 pm Hi all, forgot to post back, regarding the overcharging,I replaced the electronic voltage regulator, cleaned all the earth's up in the engine bay, added a earth lead from the alternator to the inner wing,and all is good now, not sure if it was the regulater,or a bad earth, but I think it may have been that the voltage regulator,as there had been a trace of water inside it, thanks again for all the replys,

I also changed the battery cables. I now have TOPDC jumper cables in my garage. Although, I still need to buy a number of devices, but I will gradually complete the garage with everything I need.