Latest victim of the AMP gauge ambush! No damage but confirmation on fix pls..

[K9COP]

The words 'bullet' and 'Dodged' spring immediately to mind....


OK, so my dear '69 suffered what I think is the AMP gauge failure yesterday...

Bless her, she waited until I was right outside my garage before, when I engaged reverse, absolutely everything died! No smoke or even burning smell (although I've lost my sense of smell since I was run over on duty... ) just a complete failure and car cutting out... did the reverse lights finally tip the balance? I had radio, lights, wipers, fan, sat nav etc all on....

I disconnected the battery, and pushed her into the garage and stepped away for the evening. I came on here (the forum), and as usual, knowledge gold was found. It was reassuring to know that it was probably not a unique fault.

Today I removed the radio blanking plate and had a good search round. No burnt wires (Like Troy's on Dana) and apparently no burnt wires or fusible links under the bonnet either. I bridged across the two terminals on the back of the amp gauge, and 'voila', she started right up (off a booster pack as the battery was flat - drain from the failed gauge?)...

Anyway, I removed the two terminals from the back of the gauge and then reattached them temporarily to one post. All is well, and am I crazy or are the bonnet mounted turn signals brighter? 

So my question is, is the MAD write up for by-passing and rewiring the gauge/loom still the prevailing wisdom? I found the thread here:

http://www.madelectrical.com/electricaltech/amp-gauges2.shtml

And it seems to make sense to me. I have a spare voltage gauge in the aftermarket trio containing oil pressure and coolant temp that the previous owner installed under the 'under the centre dash' mounted radio. Maybe I'll try and move it up to the AMP gauge location, or just hook it up and leave it be.

There is a second hand OEM dash harness on Ebay for $40, I'm tempted to buy it to allow me to replicate it with new wire and then just 'plug and play' swap for what's in the car, assuming it's the same of course.

The previous owner (apparently honest chap) told me the wiring is all original, so, as there appears to be various additions/mods, I'll make a long/medium term task of swapping out/re-routing all the wires as I go. Also thinking of having the cluster out, just to make sure all is well behind there...

Couldn't actually determine what was the 'fusible link' under the bonnet. Can anyone oblige with a pic please? What amperage of fuse would replace the main fusible link?

I bought new links, inline fuse holders, battery quick disconnect, and most important of all, a nice big fire extinguisher that now resides behind the passenger seat! 

Our Forum -1, all consuming flames -0, for now.

All advice gratefully accepted guys. Thanks, CS

[Nacho-RT74]

as any other part of the car, needs mantenience... and some upgrades adviced. But it seems nobody cares about a good electrical system conditions ( hence all the splices made all around in lot of cars ) or not to pay attention to the electrical system until fails.

The SAFEST WAY to keep your charging system healthy, is get an alternator able to feed the car demands. Once you get thta, rest is piece of cake.

http://www.dodgecharger.com/forum/index.php/topic,33574.0.html

[twodko]

I would also urge you to buy new wiring harnesses, never used ones.

[K9COP]

Nacho, thank you, I read all the way through your thread before I posted. Very very interesting, thanks for posting it. I'm looking to properly upgrade/maintain the system so my girl doesn't get toasted. I like the thought of replacing all the wiring so I can be at least a little more confident.

Twodko. I agree with your advice but I mentioned the Ebay harness to use as a template to allow me to construct a new one, not to install the used one in my car, and then install the new one in my car once constructed, minimising down time.

Thanks guys,

CS

[Nacho-RT74]

Is just about regular mantenience like the rest of car. a Car lives with electricity, not just gas or tires. Everybody spends $1000 in tires when they look worn due the use, abuse, heat and missaligment... Heat, rust, dust also damages electrical parts, just that nobody checks that untill really fails

[K9COP]

If I was to put an inline fuse in the leads running to and from the AMP gauge (Now bypassed and the wires connected to one post) what amperage fuse would be required please?

Thanks guys,

CS

[b5blue]

Starting ANY car with a dead battery is BAD. No car was ever built to charge a dead battery. It's only function is to start the car. It's a sure one way ticket to a wire roasting BBQ. Recharge the battery before trouble shooting from now on. 

[K9COP]

Great advice, thanks Neal. I do accept I've been a little complacent by not concentrating on the wiring, and just assuming it was all OK, but lesson learned....
Thanks,

CS

[Pete in NH]

Hi,

I'm a retired electrical engineer and thinking over your idea of installing fuses in the ammeter lines does not strike me as the way to go. As I recall the highest value in-line fuse I've seen is 30 amps which is lower than the highest value of current in that circuit. So, you might see a lot of nuisance fuse failures where no fault exists. Even if higher value fuses are available the fuse will still allow a high value of current to flow through the bulk head connector contacts and heat them up, possibly melting them. Nacho's bypass upgrade, which is what Chrysler did on fleet cars and taxis is the way to go. You want to take the load off those bulk head connector contacts and lighter gauge factory wiring. I've always been amazed at how light gauge the wiring from the alternator output is and that Chrysler got away with it. There is very little reserve in the system and now that the wiring and connectors are 40 years old, time and corrosion are taking their toll.

By the way since you bypassed the ammeter at the dash board and things have come back to life, I think that's a good indication that the ammeter instrument itself has failed and gone open circuit. I think I would replace the ammeter, install the bypass up grade, clean the bulk head connectors and call it a day. One of the problems with the fuse idea is that once you get to really high current value fuses in the standard automotive types is that you run into the same high current through a small contact surface you have with the bulk head contacts.

[K9COP]

Hey Pete, thanks so much for the post. I completely agree with all you say. Something in my layman's mind used to say 'a fuse will save me' but now you've explained it, I agree with what you say. I intended to go with the bypass/upgrade anyway, and to be honest, I'm just really thankful that she didn't go up in smoke.
I like your approach, and I'll take your advice.

Welcome to the forum! There is a lot of excellent advice and information on here, and I have a feeling you will be able to contribute greatly to that.

Thank you.

CS

[Pete in NH]

Your welcome, and thank you for your welcome to the group. Yes, the formum certainly does seem to have a really great group of Charger enthusiasts and a lot of collective knowledge. I think your original post summed it up on dodging a bullet, I'm running the same risk on my 71 Charger right now and will be installing the bypass modification on mine really soon! Right now I'm tackling some brake system maintenance so i can get the car out for the spring time weather here.

[Budnicks]

there's a good, tech article good automotive electronics/electrical connectors, wires, supplies, schematics, relays, diagrams etc., try Mad Enterprises @ www.madelectrical.com/

[K9COP]

Coolio, thank you. 

CS

[Pete in NH]

Hi,

I did a little more research on this topic and found that Littlefuse does indeed make a fuse suitable for this application, they call it a Maxi Fuse and it is available in ratings up to 80 Amps. I also learned that Chrysler used these fuses in newer cars to replace fusible links that were used in our cars. My 71 shop manual shows fusible links in one side of both the standard wiring and the 60 amp fleet upgrade wiring at the battery feed point, which would be the stud on the starter relay. My car has a Blue (16 GA.) fusible link , at this point, with the 45 amp alternator. I would think a 16 gauge wire would melt at something around 50 to 60 amps.

My original concern was that a standard 30 amp auto motive fuse would not work in this application, but, a Maxi fuse sized at something appropriate for the alternator on the car would indeed work and provide basic fire protection.

[K9COP]

Hey Pete, more great advice and thanks for the effort. So, using your post, are you saying that I could put a 50 or 60 amp fuse inline, in place of the fuseable links? Like say, in the wires that run (ran) up to the AMP gauge? Sorry if I'm being a bit slow on this, but if that would work, then that would be a nice and tidy solution for me. I still think the MAD upgrade/re-route is also worth doing.

Thanks for going the extra mile, a very worthy addition to the forum IMO. 

CS

[Budnicks]

Hey Pete, more great advice and thanks for the effort. So, using your post, are you saying that I could put a 50 or 60 amp fuse inline, in place of the fuseable links? Like say, in the wires that run (ran) up to the AMP gauge? Sorry if I'm being a bit slow on this, but if that would work, then that would be a nice and tidy solution for me. I still think the MAD upgrade/re-route is also worth doing.

Thanks for going the extra mile, a very worthy addition to the forum IMO. 

CS

[Rolling_Thunder]

I would also check the wiring at the firewall connector on the inside of the cabin.   On a 1966 Plymouth VIP we had a similar problem.   The fusible link was fine - took a look under the dash and the power feed wire had melted at the bulkhead connector. 

[WHITE AND RED 69]

I added one of these painless maxi fuse in my 69 with my 100 amp alternator.

http://www.summitracing.com/parts/prf-80101

I'd also recommend sending your cluster to Redline gauge works and have a volt gauge conversion done to the amp gauge. Costs about $125 but well worth it.

[K9COP]

Thanks guys... will do. 

CS

[Pete in NH]

Hi Everyone,

After my last post I was troubled by the fact that the engine compartment wiring diagram for my 71 seemed to show both the original ammeter wiring through the bulk head connector and the 60/65 Amp upgrade wiring in parallel with two fusible links. This theoretically could allow twice the current through the ammeter and car wiring before fusible links started to blow. NOT GOOD! Chances are that something would blow before this happened, one link would blow first and the second would follow very shortly. But, it would be a poor design. So, I went back to the shop manual and did some more digging. I found the answer a few pages later in a small special diagram of the 60/65 amp alternator installation. A little note on the diagram gives instructions to cut the original circuit wiring at the bulk head connector and tape the wires.
This would leave only the upgrade wiring in the circuit with only one fusible link. So, the Chrysler engineers did indeed get it right! It would also seem they are saying the original ammeters, at least in 71's can handle 60/65 amps. They show one leg with #8 gauge wire and the other with #10 gauge. I would use # 8 for both sides.

So, now that I have all this sorted out, this is how I'll be upgrading my 71.-

1-   Remove the blue fusible link connection at the starter relay stud and unplug the other end of the fusible link.
2-   Remove  the Black wire at the alternator output stud and tape off to the side.
3-   Run a new #8 gauge Black wire from the alternator output stud to the ammeter stud with a black wire.
4-   The #12 Black wire on the ammeter stud remains in place, but trace it to the spice and find the #12 Black wire that leads to the bulk head connector from the splice and disconnect it.
5-   Run a #8 gauge Red wire from the ammeter stud with the Red wire and remove the original Red wire. Tape the original Red wire back to keep it out of the way.
6-   Connect the new #8 gauge Red wire through a 50 or 60 amp Maxi Fuse to the starter relay battery terminal.

This modification will completely remove the bulk head connector wiring from the circuit, eliminating that potential problem and give proper fusing in the new circuit. I don't like the idea of cutting wires out of the original harness and prefer to just tape them off out of the way, but you could cut them if you prefer. The new Maxi Fuse becomes the master fuse for the whole car. My car has the original 45 amp alternator on it, so a 50 or 60 amp fuse should work. If your alternator is above 60 amps I would go with a voltmeter conversion, which would change the whole set of instructions above. Remember to disconnect the negative battery terminal before doing any of this- fewer fireworks that way!

[69wannabe]

Would Nacho's parallel wiring not be a good fix/preventive fix for an already good working charging system?? I just had some issues with my voltage regulator which I eliminated by going with a new power master one wire mopar style alternator. My alternator gauge still works fine with this alternator but I don't know for how long. I was planning on running the parallel wiring on my 68 charger which should reduce any heating of the wiring where it goes through the bulkhead connector and having the extra fuse link should give extra protection for the main wiring to the battery too. Only concern is can the original alternator gauge handle the extra amps from the new alternator which is rated at 75 amps?? Nacho's wiring addition makes sense to me and it would reduce a lot of stress on the already old factory wires by just adding new wires basically running with them just not through the bulkhead connector!!! I could always put an inline fuse in between the alternator and the gauge but I am not sure how necessary that would be if I got two fuse links coming from the battery side of the gauge. I need to upgrade this part of my car for sure and don't need this thing to go up in flames randomly. I have heard so many horror stories bout this problem and it always keeps mopar owners wondering when its going to affect us. Would like to get a fix on it before it zaps mine like it has others!!!!

[Pete in NH]

Hi,

Take a careful look at my last post and its first paragraph. There are issues with two parallel wiring paths, one being they could direct the full 75 amps of your alternator output through your ammeter with neither of the fusible links or fuses blowing. I don't think the ammeter could handle the full 75 amps for very long without failing. that is why I suggested going to a voltmeter conversion when going with an alternator much above the stock 45 amp units. Your on the right track to be concerned about upgrading the wiring, with that bigger alternator you might want to consider the voltmeter conversion. You need to look at these electrical systems as a carefully balanced system and be careful not to let one side get out of balance with the other parts of the system. The problem with new high current output alternators in these old electrical systems is they do indeed unbalance things.

[69wannabe]

I see your point Pete about over loading the alternator gauge. That's what I was afraid of by doing the parallel wiring. Do you have any info on the voltmeter conversion?? I have heard alot bout a voltmeter conversion but haven't really seen or heard of many people doing it. Thanks, Chad.

[Nacho-RT74]

2 notes:

1- fuse link just on batt side is enough because is the only source able to feed a short... on a short, the alt simply isn't enough to feed the load. In other words, if you were running a car without a batt and just alternator, any short will stall the engine, so no more source for any short around. that's why just the batt side is protected

2-the parallel wires ( or bulkhead bypass if you want to remove the existant ones on bulkhead ) is just PART of the solution. BUT a bigger alt is the definitelly solution to save the Charging system.

A bigger alt doesn't mean will feed all the output capacity. The alt will feed just the car demand. You can get a thousand amps alt, but if car demands just 55, the alternator will feed just those 55 amps.

Where is the problem with stoker old amps ? they aren't enough to feed AT IDDLE. Since they aren't able to do it, battery provides the failed load by the alternator ( discharge reading ). THEN when giving RPMs, the alt will suply the power for the car AND what battery lost ( Charge reading ) This back and forth ammeter dance is the fail on ammeter due the heat by the load

if the car requires 60 amps to work, the battery is full and alternator is able to feed the 60 amps at any RPMs, the ammeter WILL NEVER sense anything ( of course when everything is correctly sourced from alt, never from batt ), because battery is never getting charged or discharged. No load thorught the amm, no heat there. At this moment is when the bulkhead bypass or parallel wires saves everything to hold the 60 amps load. It doesn't matter if ammeter is 40 amps capacity.

Remember there is a missconception made from factory about the ammeter being an alternator gauge where REALLY IS a batt gauge

another trick... GET A BALANCE ON BATTERY CRANKING POWER when selecting one! never get a BIG cranking capacity battery on stock alt, because in a temporally discharge ( for whatever reason ) the alternator will take more time to recharge the batt, producing more heat at amm. is BETTER a smaller batt capacity on system, than a bigger one... unless you have upgraded the alt accordingly!

[Nacho-RT74]

I need to post another thing... I noted that dual fuse link it can be a mistake, if the fuse link gauge is incorrectly selected. If keeping both wires going to batt, dual fuse link is a demand BUT smaller gauge accomplished with it ( I learn step by step LOL )... I need to correct that on my link.

originals are 16... maybe dual 18 will be better than dual 16s or one 16 and one 14 like I posted there, which will be worst.

got it ?

OR maybe splice both red wires into  just one 14 gauge fuse link will be a nice way to go, like MaMopar did back in the years when big alts on a highly optioned cars, and just used the bigger gauge wires, not the ones on bulkhead ( which is the original idea )

Remember once more, I made it PARALLEL, because you don't need to remove your existant ones if still in good conditions, but originally the thicker ones were the only ones used on these cars.