Ammeter to Voltmeter...who does it?
- Thread starter billytuffnuts
- Start date
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...and because the Amp meter is always hot, be sure to disconnect the battery.
67Dart273
Well-Known Member
Since you have the cluster out, there's a few things you should consider doing, no particular order
1...Did you do some sort of ammeter bypass, other than just bolting the wires together?
2....Cluster is "not very well grounded" OEM, by the mounting screws. Add a grounding pigtail from a common point on the PC board and bolt to the column support or dash frame
3....If you have not replaced the gauge regulator/ IVR, this would be the time
4....Check the harness to board connector pins and repair / solder as necessary
5....The spring fingers that form the socket for the gauge IVR should have jumpers soldered across to the board traces
6....Gauge stud nuts can get loose or corroded. Loosen/ tighten them several times
7....Obtain a rheostat or test resistances and check gauges accurasy
8...Certainly the time to replace and do maintenance on lamps. Clean the board where the sockets contact, eraser, etc, and clean or replace sockets, consider replacing bulbs. Some guys like LEDs but there can be problems with the dimmer on them.
1...Did you do some sort of ammeter bypass, other than just bolting the wires together?
2....Cluster is "not very well grounded" OEM, by the mounting screws. Add a grounding pigtail from a common point on the PC board and bolt to the column support or dash frame
3....If you have not replaced the gauge regulator/ IVR, this would be the time
4....Check the harness to board connector pins and repair / solder as necessary
5....The spring fingers that form the socket for the gauge IVR should have jumpers soldered across to the board traces
6....Gauge stud nuts can get loose or corroded. Loosen/ tighten them several times
7....Obtain a rheostat or test resistances and check gauges accurasy
8...Certainly the time to replace and do maintenance on lamps. Clean the board where the sockets contact, eraser, etc, and clean or replace sockets, consider replacing bulbs. Some guys like LEDs but there can be problems with the dimmer on them.
French demon
Well-Known Member
Hi
Please, can you explain :
"1...Did you do some sort of ammeter bypass, other than just bolting the wires together?"....?
Please, can you explain :
"1...Did you do some sort of ammeter bypass, other than just bolting the wires together?"....?
67Dart273
Well-Known Member
The purpose of a voltmeter is to have a gauge that is meaningful, BECAUSE you bypassed the ammeter, and the reason for doing the bypass is "if" or "that you suspect" that harness and connector damage has or will occur because of high current. The more accessories you've added and the higher the alternator output (50A or more) the more likely this is to occur
Start by reading the MAD article. If you do not do the bypass as they did, this article at least points out some of the reasons and problems
Catalog
Below is the simplified diagram of primary power from that page
Every single terminal and connector in the path from the alternator to the battery, and to the various loads, AND the smaller size of original wiring is a potential problem. "The Usual Suspects" are the bulkhead connector terminals, the ammeter terminals and the guts of the ammeter itself
There are basically three strategies to either improve the situation or to bypass the ammeter, in no particular order:
1....The MADD method
2....Some of us basically run a new, larger wire from the alternator to the battery WITH AN appropriate fuse or fuse link
3....The factory had a bulkhead connector bypass known as "police/ fleet/ taxi" wiring which is documented in some service manuals. Look up about a 69--72 service manual (at MyMopar) and lookup Belevedere/ Fury etc "optional 65A alternator) and you'll find that the factory? dealer? modified the wiring, and ran larger wiring through the firewall on SEPARATE grommets, not using the bulkhead connector
Start by reading the MAD article. If you do not do the bypass as they did, this article at least points out some of the reasons and problems
Catalog
Below is the simplified diagram of primary power from that page
Every single terminal and connector in the path from the alternator to the battery, and to the various loads, AND the smaller size of original wiring is a potential problem. "The Usual Suspects" are the bulkhead connector terminals, the ammeter terminals and the guts of the ammeter itself
There are basically three strategies to either improve the situation or to bypass the ammeter, in no particular order:
1....The MADD method
2....Some of us basically run a new, larger wire from the alternator to the battery WITH AN appropriate fuse or fuse link
3....The factory had a bulkhead connector bypass known as "police/ fleet/ taxi" wiring which is documented in some service manuals. Look up about a 69--72 service manual (at MyMopar) and lookup Belevedere/ Fury etc "optional 65A alternator) and you'll find that the factory? dealer? modified the wiring, and ran larger wiring through the firewall on SEPARATE grommets, not using the bulkhead connector
French demon
Well-Known Member
Thank you very much, the MAD article is very interesting and useful 
RioGrandMan
Well-Known Member
Thanks for the discussion on this.
I made a gauge swap from amp to volt. I'm now planning to cut and sodder the old amp meter wires and run the voltmeter power off the back of the ignition.
Any thoughts or experience (good or bad) is welcome.
Thanks
I made a gauge swap from amp to volt. I'm now planning to cut and sodder the old amp meter wires and run the voltmeter power off the back of the ignition.
Any thoughts or experience (good or bad) is welcome.
Thanks
moparmat2000
Well-Known Member
If you run the negative volt meter mount stud grounded to the metal cluster housing then you only have to run 1 wire for the 12V feed. Make sure your 12v feed stud is insulated so it doesnt ground out. I'm not well versed in the 66 plymouth cluster. Does it have a plug in IVR on the circuit board? If so, find the side of the IVR that's the 12V feed side, and attach your 12V feed wire to that side of the circuit board.
RioGrandMan
Well-Known Member
Instrument Voltage Regulator, aka dash limiter. Along with the ammeter, it can be a source of trouble. While you've got your instrument panel apart consider upgrading to an electronic version. A member is making and selling them on this forum.
Also available at: MOPAR Products
Here's some info from RT Engineering's webpage:
On the back of most mopar dashes (with some notable exceptions) there is a 1" X 2" metal can, with 3 terminals. This device is known as a limiter. Its function is to regulate the voltage that is being applied to the fuel/oil/temperature gauges.
Some mopar dashes don't have a visible limiter device. Instead they have the limiter built into the fuel gauge. These special dashes can be identified by looking at the fuel gauge, and if it has 3 terminals then it has the limiter built in. A-Body Rallye dashes and 66/67 Chargers are two examples of dashes that have the limiter built into the fuel gauge.
RioGrandMan
Well-Known Member
Oh, thanks! Yes I know from memory I have that, I think it's below the fuel gauge on the back.
RioGrandMan
Well-Known Member
I pulled this off the internet, but it's just like mine. Is this the IVR?
OK, focusing on the fuel gauge... One of 3 studs has the noise suppression cap' added on it (prevents noise in radio speaker) The wire in the harness connector there (in line with the harness connectors locator) is switched 12 volts into the Mechanical limiter inside the fuel gauge. Top center stud with a square hole in the board and strange clip over it is the pulse voltage for the fuel gauge and the temp gauge. Lower right stud is connected to the fuel sender wire (should be a blue wire in the harness connector there).
Small details... The square hole in the circuit board and strange clip covering it and that stud is all about ventilation/cooling. Two resistor windings inside one small gauge can is a good bit of otherwise captured heat.
The engineers later determined that all of this wasn't really necessary. Later examples such as 67 up rally panels had a notch cut out of the top of the gauge can (heat rises) and a Bakelite cap over that warm stud through a typical round hole.
The more you know... Notice the temp gauge has only 2 studs. That is a common gauge. The only current path there is from stud to stud. Only path to ground for the pulse voltage is at the temp sender. The fuel gauge has 2 studs that serve the same purpose. Pulse voltage from limiter goes to ground at fuel sender.
So with the switched 12 volts also going into that gauge, where does it go to ground? Lift this gauge from the instrument panel and look at its backside. There is your 4th connection. A small strip of metal contacts an unpainted spot in bottom of the housing to provide a chassis ground path for the mechanical limiter.
There is a simple way to disable and isolate the original mechanical limiter inside that gauge and add on a solid state regulator but since so many members here are soooo quick to point you to the RTE website and their instructions to open the fuel gauge and bend something, I regress. Good luck
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