Hot ballast resistor and pinned Rallye gauges.

[Todd502]

My 1970 Duster 340 has been converted to electronic ignition. The car has been sitting for years partially put together.(I recently purchased it) When I start the car the ballast resistor gets hot to the touch and the gauges are pinned.
The car can be hard to start because the carb needs to be gone through because of sitting for years since being rebuilt.
Any thoughts?

 

[4spdragtop]

In a rally gauge scenario , the fuel gauge has a voltage reg/limiter inside of it.
That could very well be the problem.
There are elec gurus that will help you, but what I can offer is factory manuals.
They can be found at mymopar.com
Get a service, as well as parts. Specifically you need schematics. Unhook your battery until its figgered out....
Good luck.

 

[4spdragtop]

Ballast resistor getting hot is normal. Its a resistor.

 

[Kendog 170]

Agreed
Ballast Resistors

Also there is a Voltage limiter that feeds the Instrument panel but someone else needs to chime in that know more. Good luck. Does your Amp. gauge work?

 

[4spdragtop]

No external VR on rally gauges. Its internal(unless modified) inside the fool gauge.

Agreed
Ballast Resistors

Also there is a Voltage limiter that feeds the Instrument panel but someone else needs to chime in that know more. Good luck. Does your Amp. gauge work?

 

[Todd502]

I believe the amp gauge works but I'm not entirely sure.

 

[Murray]

Remove gauge grounds (fuel sender, temp sender) to see a change. If not, then problem is elsewhere.

 

[Todd502]

I disconnected the water and oil sending units (easy access) and the gauges don't respond at all with the ignition on.

 

[67Dart273]

That proves you have broken the circuit. Since two gauges pin, that implies the IVR is bad, which, again, is inside the fuel gauge on a Rallye cluster. You need to pull the cluster and fix it. Gauges are expensive and difficult to find. They are easy to blow up.

Here's a bit from RTE, who make and sell electronic replacements for the OEM IVR

MOPAR Products

RTE Gauge Faq - rte

Redfish, on here, is an absolute expert on clusters, and says that you do not need to open up the fuel gauge to convert to electronic. Figure a way to isolate the fuel gauge from ground and that will completely disable it. What you had, origininally, is 3 terminals on the fuel gauge. One was a 12V switched feed from the key, fed 12V to the limiter inside. It limited/ regulated power for the gauges, fed the fuel gauge internally, and brought that regulated power out to a second terminal on the fuel gauge. That terminal then fed regulated gauge power to the other two gauges, and the 3rd terminal on the fuel gauge was of course the sender

The current path is from ignition switch--to limiter---to gauges----through the gauges-----to the senders, fuel, oil, temp, and to ground.

The ammeter is completely separate

 

[Mattax]

I believe the amp gauge works but I'm not entirely sure.

It is seperate from the others, but you should know if it works because
a) It's a critical part of the battery circuit.
b) It will indicate when something is wrong or going wrong in the power.

Engine off, turn the dome light on and step on the brakes. The needle should noticably move to discharge. Same idea with parking lights and headlights. With headlights and parking lights both on it should show around 10-12 amps discharge.

Leave the other gages disconnected so they don't get burned out.
Start the engine. The needle should show slight discharge to the ignition, then when the engine starts the needle should move to charge. It then should slowly but visibly move toward the middle.

If it doesn't do these things, then we can address that.

 

[Mattax]

I disconnected the water and oil sending units (easy access) and the gauges don't respond at all with the ignition on.

Crawl underneath and disconnect the fuel gage for now. Either remove the wire connector or remove the ground clip - whichever is easier. This way the gage won't get damaged.

 

[Todd502]

Thanks for all the input guys. Appreciate it.

 

[Kendog 170]

I was waiting for Mattax and 67Dart273 to show up. My knowledge is Limited.