Ammeter bypass

[bronze turbine]

Is this something that is important to do if everything in the car is factory stock? I've heard it should be done if you upgrade the alternator and start pulling a lot more amps than the factory wiring was designed for. I'm guessing the only reason they catch fire is because the connections on the ammeter get loose and get hot?

 

[MoPar~Man]

The instrument cluster amp meter is wired so that all current from (or to) the battery to anything else (except starter motor) flows through it, I think even when there is no key in the ignition. This includes alternator charge current. Ford and GM did not do that (or they stopped doing that way before Chrysler did). Chrysler felt that was a better indication of the condition of the electrical system vs a volt meter.

The firewall contacts and the amp meter itself could fail and cause a fire, I think that's the big issue here. An unnecessary risk given the perceived benefit of having the amp meter.

 

[330dTA]

In a word, yes.

 

[SPF Required]

It is also important to remember that while most of the fine executives at Chrysler in the day likely loved these cars, they still needed to prioritize profits. From everything I have learned, the wiring in or beloved cars is probably slightly undersized for the current it needs to carry. Using smaller wires, saves costs and improves the bottom line.

Just my opinion…

 

[Big_John]

Is this something that is important to do if everything in the car is factory stock? I've heard it should be done if you upgrade the alternator and start pulling a lot more amps than the factory wiring was designed for. I'm guessing the only reason they catch fire is because the connections on the ammeter get loose and get hot?

IMHO, much of the hysteria you'll read about the ammeter is grossly blown out of proportion. It really comes down to poor connections and wire size.

The thing that has not been asked is what your car is. And I apologize for not remembering... But that is important. For example, some of the cars have a "shunted" ammeter that doesn't run as much current through the ammeter. Another bad spot (and probably cause for much more havoc) is the power wire on the 70(?) and up steering column. I've yet to take one apart that wasn't burnt at least a little. Another issue is the wires on the ammeter just plain being loose, and loose causes more resistance which does end up as heat.

That said, the "bypass" isn't a bad idea by any means and if you want to do it, great... The wiring and connections at the bulkhead are getting pretty old and running most of the charging current through some under hood wiring makes a lot of sense and is never a bad idea. Does it need to be done? If everything is good, and you don't have the high current draw, it's probably not going to matter. I have one car that it has been done on and that was mainly because I have some higher draw stereo junk. The other two have not had it done.

There are people that will disagree with me, but whatever...

And great that you said "ammeter" instead of "amp gauge". Correct terminology is always good.

 

[bronze turbine]

The thing that has not been asked is what your car is.

Sorry. It's a '68 Chrysler 300.

 

[cbarge]

Sorry. It's a '68 Chrysler 300.

Having owned several 68 C bodies yes I strongly recommend doing the bypass.
Here is the simplest way..

 

[bronze turbine]

Thanks! That was very helpful!