Troubleshooting gauge cluster

[Smokinnjokin]

I have the cluster out of my '67 Satellite, having the bezel re-chromed and now is the time to do some troubleshooting. My temp gauge doesn't work, and fuel gauge only reads 1/2 when full. Aftermarket sending unit possibly the culprit.

Now that I have the cannon plugs unplugged from the back of the instrument cluster and easily accessible, this is a good time for me to t-shoot the wiring harness (more likely culprit than the instrument cluster I think). I am really, really stupid when it comes to electronics, so back me up here.

1) Temp - if i ground the sending unit, and get my continuity tester and put it in the correct socket on the cannon plug for instrument cluster, good continuity means wiring harness is OK, correct? I should then check sending unit and instrument cluster? Sending unit and engine wiring harness are new, so if theres an issue it's likely between bulkhead and instrument cluster. Now that the cluster is out I can see/reach back there easily.

2) fuel gauge - checked the new sending unit for sweep and ohm reading before installing, I forget what the range was but it checked out. Reads 1/2 when full. Is there any possibility there is something wrong in the instrument cluster? I was thinking about a Tanks reprogrammer, fairly inexpensive fix if something is up with the cluster.

3) speedo rebuild. The speedo needle bounces. Its mildly annoying, but not really worth waiting months and paying $$$$ for a instrument place to rebuild. How difficult is this to rebuild, specialized tools required I assume?

4) voltage limiter - I have no idea what this thing actually does. Should I replace with an RT-eng solid state limited while the dash is out? I NEVER, EVER, want to take the instrument cluster out again if possible. Its a pain, the plastics are delicate, and I am a big fan of do it right the first time. Could this be causing my fuel and temp gauge symptoms? I am 99% sure this is the first time cluster has been out and everything is original.

 

[AR67GTX]

Definitely get a solid state voltage regulator. The speedometer probably needs a head kit. Check around town and see if you don’t have a local speedometer rebuild place. It would probably be a lot faster and cheaper. If you go through the wiring diagram in the service manual you can identify which pins in the two 5-pin connections are power for lighting, turn signals, oil pressure light, etc and using to home made wire jumpers back to your battery for power and ground, you can see if any circuit connections are bad. Sounds like you fuel gage issue is probably the sender in the tank but there are good instructions in the service manual on checking gage response. You can check on line and find a small bottle of fluorescent Orange needle paint and repaint your needles which really helps the appearance. Hopefully the rest of the gage faces are OK wit just a little dust off and cleaning any places that need it with just a water-dampened soft cloth. Good luck. I hate electrical stuff too.

 

[twecomm]

Not a Plymouth guy, but this is how the gauges work in this era Mopars similar to my 66 Charger. The gauges, oil pressure, fuel and temp gauges operate basically the same. They operate on an electro-thermal principle. Inside the gauges, many turns of a special type of insulated resistance wire is wrapped around a small flat piece of certain bi-metal or certain alloy metal. When this wire has a voltage applied, the current flow causes a slight heating in the wire, this heat causes the metal it's wrapped around to expand, or bend, and move the gauges needle. The stock voltage regulator is a mechanical device. It's probably defective, but if you have the cluster out, get the all solid state RTE electronic voltage regulator and install it !! Basically, the regulator, mechanical or electronic, takes the nominal 12 V battery voltage and reduces it to aprox. 5 volts. When the car is initially started, the regulator applies the full battery volts to the gauges, but just for a few seconds to get the gauges to more quickly provide readings. After those few seconds, the regulator output is a pulsating 5 volts, in that it turns on and off in short intervals. That pulsating 5 volts output of the regulator is applied to one side of the three gauges previously mentioned. The other side of each gauge goes to it's respective sender which provides a variable resistance with pressure or temperature change. In the fuel sender, it's the physical movement of the float arm that adjusts the resistance of the variable resistor of the fuel sender. The fuel senders round ring is the ground and must have a good ground connection. The threaded housing of the temp and oil pressure gauge is ground, or battery minus. Pressure and temperature senders have a certain internal resistance at ambient temperature. As pressure/ temperature rises, this resistance decreases causing more current to flow in it's respective gauge, thus higher reading.
Note : Speedo and Tach operate differently and DO NOT connect to the 5 volt regulator.

 

[bandit67]

Make sure your bouncing speedo needle is NOT because of a worn speedo cable or driven gear. But I agree, do all the maintence/rebuild NOW while it out.

 

[AR67GTX]

You can beg, borrow or buy a new cable from someone, install it to the speedometer and spin it with an electric drill on the cable. If the speedo jumps around your speedometer head is probably bad. If not, then your old cable or possibly the driven gear in the transmission is likely bad.

 

[Smokinnjokin]

You can beg, borrow or buy a new cable from someone, install it to the speedometer and spin it with an electric drill on the cable. If the speedo jumps around your speedometer head is probably bad. If not, then your old cable or possibly the driven gear in the transmission is likely bad.

Speedo gear in the trans, and the cable are new. New cable helped a bit with the bouncing, but its still there. Not terrible, its only below 5mph or so.

Not a Plymouth guy, but this is how the gauges work in this era Mopars similar to my 66 Charger. The gauges, oil pressure, fuel and temp gauges operate basically the same. They operate on an electro-thermal principle. Inside the gauges, many turns of a special type of insulated resistance wire is wrapped around a small flat piece of certain bi-metal or certain alloy metal. When this wire has a voltage applied, the current flow causes a slight heating in the wire, this heat causes the metal it's wrapped around to expand, or bend, and move the gauges needle. The stock voltage regulator is a mechanical device. It's probably defective, but if you have the cluster out, get the all solid state RTE electronic voltage regulator and install it !! Basically, the regulator, mechanical or electronic, takes the nominal 12 V battery voltage and reduces it to aprox. 5 volts. When the car is initially started, the regulator applies the full battery volts to the gauges, but just for a few seconds to get the gauges to more quickly provide readings. After those few seconds, the regulator output is a pulsating 5 volts, in that it turns on and off in short intervals. That pulsating 5 volts output of the regulator is applied to one side of the three gauges previously mentioned. The other side of each gauge goes to it's respective sender which provides a variable resistance with pressure or temperature change. In the fuel sender, it's the physical movement of the float arm that adjusts the resistance of the variable resistor of the fuel sender. The fuel senders round ring is the ground and must have a good ground connection. The threaded housing of the temp and oil pressure gauge is ground, or battery minus. Pressure and temperature senders have a certain internal resistance at ambient temperature. As pressure/ temperature rises, this resistance decreases causing more current to flow in it's respective gauge, thus higher reading.
Note : Speedo and Tach operate differently and DO NOT connect to the 5 volt regulator.

What would symptoms of a faulty regulator be? My ammeter is bypassed, so i suppose temp and gas gauges are the only thing it runs anymore.

 

[Smokinnjokin]

Definitely get a solid state voltage regulator. The speedometer probably needs a head kit. Check around town and see if you don’t have a local speedometer rebuild place. It would probably be a lot faster and cheaper. If you go through the wiring diagram in the service manual you can identify which pins in the two 5-pin connections are power for lighting, turn signals, oil pressure light, etc and using to home made wire jumpers back to your battery for power and ground, you can see if any circuit connections are bad. Sounds like you fuel gage issue is probably the sender in the tank but there are good instructions in the service manual on checking gage response. You can check on line and find a small bottle of fluorescent Orange needle paint and repaint your needles which really helps the appearance. Hopefully the rest of the gage faces are OK wit just a little dust off and cleaning any places that need it with just a water-dampened soft cloth. Good luck. I hate electrical stuff too.

The faces/numerals are actually perfect! Needles are faded but thats it. Everything is dusty and in need of a good cleaning.

 

[Smokinnjokin]

Does anyone have a reputable speedo repair shop to reccommend in the greater nashville, clarksville TN area? My local speedo shop here in town won't touch it.

 

[twecomm]

The amp, or alternator gauge does not use the 5 volt from the gauge cluster voltage regulator. Just oil pressure,gas and temp gauges use the 5 volts. The original regulator is mechanical. If the original type regulator is bad, it's possible that it could be dead and not making any voltage output meaning the mentioned gauges wont work. If the regulators internal points get stuck, or welded together, it can put a full 12 volts to the gauges all the time and will eventually toast the innards of the gauges that use the 5 volts. If working properly, and the points are opening and closing creating the pulsating 5 volts it's working.
Best bet is to get the solid state RTE unit, you wont regret it.