Wiring Help!!

[Joel Talka]

Sorry, This will probably be a long one...

I've been working on my 66 Coronet for almost 2 years now, rebuilt or replaced just about everything. Included in all this were all the wiring harnesses; main, front end, under hood and rear lights, etc.. basically 100%. Everything went in and connected up without a problem. Installed a new 408 small block.

I have everything together and fired the car up, runs great. I have headlights, tail lights, turn signals, brake lights and horn. My dash lights also work, dim because there are bunch of LEDs in there.

What I don't have are gauges and warning lights, zippo. When I turn the key to "on" before I engage the starter, I expect to see the brake light, oil pressure light, gas level and some sort of activity on the ammeter... nothing! I also believe that the alternator is not charging.. The battery is brand new but when I put my charger on it, charge level was only 40%.

I checked this forum earlier today and there was a thread on a problem similar to this, which talked about making sure the dash circuit board is grounded. Today I pulled the dash and there is no ground terminal. I tried grounding the dash at various points to chassis ground with no luck. There is an extra "ground" lug on the starter switch, tried grounding that as well, same result.

Right now I am basically at a dead end as far as wiring goes, I've double and triple checked all the connections which leads me to believe I may have a component problem. The voltage regulator is also new. It is one of those solid state ones dressed up to look old school. I'm thinking that or possibly the voltage limiter on the circuit board although I have never had occasion to replace one for failure.

Well, that's what I have....at least up to now.. I really appreciate any information or advice as to how next to shoot this issue. Sad part is that the car does run great..but I need to get this stuff straightened out before I take it out on the road...

Thanks in advance!!

 

[BeepBeepRR]

Check your board on the back of the cluster for cracks. You can trace out each gauge to each pin. Test each circuit with an ohm meter and make sure its getting continuity. This will give you an Idea. I messed up on this below. The center pin on the limiter should go down to the oil light and back over to the round connector to the 8 o clock position.

I just fixed it line is thick red.
That pin on the round connector should be 12 volts.
You should be able to ground to any of the screws that are surrounded by black lines.
Thin red line is 5 volts from the limiter. Feeds both Fuel and Temp gauges.
Oil pressure gets 12 volts from the thick red line and gets its other end from the sender in the engine compartment.
Turn signals are in Green.
Brake warning light in red on the right lower side.
Orange line indicated lights.
Light blue is fuel circuit from sender in tank.
Green line from Temp to under hoot temp sender.

 

[Joel Talka]

Check your board on the back of the cluster for cracks. You can trace out each gauge to each pin. Test each circuit with an ohm meter and make sure its getting continuity. This will give you an Idea. I messed up on this below. The center pin on the limiter should go down to the oil light and back over to the round connector to the 8 o clock position.

I just fixed it line is thick red.
That pin on the round connector should be 12 volts.
You should be able to ground to any of the screws that are surrounded by black lines.
Thin red line is 5 volts from the limiter. Feeds both Fuel and Temp gauges.
Oil pressure gets 12 volts from the thick red line and gets its other end from the sender in the engine compartment.
Turn signals are in Green.
Brake warning light in red on the right lower side.
Orange line indicated lights.
Light blue is fuel circuit from sender in tank.
Green line from Temp to under hoot temp sender.

View attachment 1495502

Wow, This is great thank you very much! I did not see any cracks in the board but was not specifically looking for them. I was concerned about pressing the connector onto those pins, the fit was tight. I'll check that.

So, with the dash in place and the ignition key "on", I should be able to see voltage at the sensor connections under the hood and back at the fuel tank..? 5 volts at the fuel and temp sensors and 12V at the oil sensor?

Do you know if anyone makes these circuit boards and gauges?

Thanks again, I really appreciate this info!!

 

[1carlover]

Hi I checked out your feed after posting my dash light issue and wanted to let you know that I have a new style 67 circuit board available if it would work in your car. It was installed for testing but is like new.

 

[451Mopar]

The entire dash is only grounded through the screws holding the cluster into the dash.
Try adding a ground wire from the gauge cluster to a known good ground.
That should help with the lights, and gauges except for the Ammeter.
The Ammeter is isolated from the gauge cluster.

 

[Nxcoupe]

Wow, This is great thank you very much! I did not see any cracks in the board but was not specifically looking for them. I was concerned about pressing the connector onto those pins, the fit was tight. I'll check that.

So, with the dash in place and the ignition key "on", I should be able to see voltage at the sensor connections under the hood and back at the fuel tank..? 5 volts at the fuel and temp sensors and 12V at the oil sensor?

Do you know if anyone makes these circuit boards and gauges?

Thanks again, I really appreciate this info!!

Yes. Another test is to have someone watch the gauges and briefly ground the sending unit wire until the gauge moves to full then remove from ground. If they don't move, but you have voltage, then the ground is suspect.

 

[Xp29h]

Wow, This is great thank you very much! I did not see any cracks in the board but was not specifically looking for them. I was concerned about pressing the connector onto those pins, the fit was tight. I'll check that.

So, with the dash in place and the ignition key "on", I should be able to see voltage at the sensor connections under the hood and back at the fuel tank..? 5 volts at the fuel and temp sensors and 12V at the oil sensor?

Do you know if anyone makes these circuit boards and gauges?

Thanks again, I really appreciate this info!!

Cracks in circuitry can sometimes be impossible to see with the naked eye. Other times they stuck out like a sore thumb! As mentioned use a multi meter for continuity first then if all checks out, then you can check that everything is getting what it needs.

Good luck! Go get those gremlins!

 

[BeepBeepRR]

If you ohm out one pin to its other end and you get continuity then you are good to go. If you ohm it out and get no continuity its possible the PCB has a break in the circuit. They do sell Modern boards here. I cant say they are any better than the old school stuff but they do make them.

Circuit Board | 1966-1967 B-Body Standard | Coronet | eBay

The cause is more than likely a bad factory circuit board. What started as a father-son restoration project (our grabber-green 1971 Superbee) has since led to thousands of Mopar/AMC enthusiasts relying on us for their restoration needs.

www.ebay.com

 

[Fran Blacker]

My 66 Satellite has a strip of steel across top cluster. It's a little longer than the 3 screws on top of cluster. It has a small 1/16" step it contacts cluster to dash frame. Left it out once no power to cluster. You don't need that piece but run a wire to ground cluster.

 

[LowBikeMike]

If you Ammeter isn't responding (showing discharge when headlights are on, not running) I believe you have something larger going on tham a circuit board or ground issue since the Ammeter is seperate from the rest of the system.

 

[Joel Talka]

If you ohm out one pin to its other end and you get continuity then you are good to go. If you ohm it out and get no continuity its possible the PCB has a break in the circuit. They do sell Modern boards here. I cant say they are any better than the old school stuff but they do make them.

Circuit Board | 1966-1967 B-Body Standard | Coronet | eBay

The cause is more than likely a bad factory circuit board. What started as a father-son restoration project (our grabber-green 1971 Superbee) has since led to thousands of Mopar/AMC enthusiasts relying on us for their restoration needs.

www.ebay.com

Thanks!! Great info!!

 

[Joel Talka]

If you Ammeter isn't responding (showing discharge when headlights are on, not running) I believe you have something larger going on tham a circuit board or ground issue since the Ammeter is seperate from the rest of the system.

I agree.. I think there are a couple of things going on here. The ammeter shows nothing. I need to start continuity checking through the firewall.

 

[Joel Talka]

Yes. Another test is to have someone watch the gauges and briefly ground the sending unit wire until the gauge moves to full then remove from ground. If they don't move, but you have voltage, then the ground is suspect.

Today I had a little time after work so I started checking a few more things..with the ignition to the "on" position..

Checked the voltage at the temp sensor. Based upon what I have learned, I should see 5V.. I see a constantly varying voltage; 4.7 down to .5, never constant. I see the same thing at the gas tank sensor lead.

Checked the alternator/regulator with the engine running.. Field is 11.6V output is 12.5V which is too low, so charging going on....

 

[Nxcoupe]

Today I had a little time after work so I started checking a few more things..with the ignition to the "on" position..

Checked the voltage at the temp sensor. Based upon what I have learned, I should see 5V.. I see a constantly varying voltage; 4.7 down to .5, never constant. I see the same thing at the gas tank sensor lead.

Checked the alternator/regulator with the engine running.. Field is 11.6V output is 12.5V which is too low, so charging going on....

That is exactly what you are supposed to see. It pulses the voltage like a turn signal blinker, so it's working. The meter works on a Hz, so depending when it samples, the voltage will be higher or lower.

 

[Joel Talka]

Sorry, This will probably be a long one...

I've been working on my 66 Coronet for almost 2 years now, rebuilt or replaced just about everything. Included in all this were all the wiring harnesses; main, front end, under hood and rear lights, etc.. basically 100%. Everything went in and connected up without a problem. Installed a new 408 small block.

I have everything together and fired the car up, runs great. I have headlights, tail lights, turn signals, brake lights and horn. My dash lights also work, dim because there are bunch of LEDs in there.

What I don't have are gauges and warning lights, zippo. When I turn the key to "on" before I engage the starter, I expect to see the brake light, oil pressure light, gas level and some sort of activity on the ammeter... nothing! I also believe that the alternator is not charging.. The battery is brand new but when I put my charger on it, charge level was only 40%.

I checked this forum earlier today and there was a thread on a problem similar to this, which talked about making sure the dash circuit board is grounded. Today I pulled the dash and there is no ground terminal. I tried grounding the dash at various points to chassis ground with no luck. There is an extra "ground" lug on the starter switch, tried grounding that as well, same result.

Right now I am basically at a dead end as far as wiring goes, I've double and triple checked all the connections which leads me to believe I may have a component problem. The voltage regulator is also new. It is one of those solid state ones dressed up to look old school. I'm thinking that or possibly the voltage limiter on the circuit board although I have never had occasion to replace one for failure.

Well, that's what I have....at least up to now.. I really appreciate any information or advice as to how next to shoot this issue. Sad part is that the car does run great..but I need to get this stuff straightened out before I take it out on the road...

Thanks in advance!!

An update,

Pulled the dash out yesterday and did all the continuity testing...no issues, it all checks out. I did find that the bulb sockets needed some cleaning but were in tact. I checked the gauges with an ohm meter and all looked OK. Before this I tested the temp gauge by grounding the sensor wire and it went full scale...so it functions. On the fuel gauge, I think I need to install a ground on the tank, it is new (painted grey), as are the straps and mat so my bet is that it does not make it to chassis ground.

The only problem I saw was that some of the screws holding the board to the frame did not have good electrical contact, I cleaned them all and retightened along with a new separate ground wire. Tested all bulb sockets to the new ground wire, great. Cleaned up all the bulb holders, adjusted the contacts and am waiting on some "real" 158 bulbs from Amazon today. I'll check each bulb functionality before reinstalling the dash...those little peanut LED will find their way to the trash.

Today, as time permits, I'll check for voltages at the connector going into the dash, that round guy with 8 active pins.

I also pulled the ignition switch and checked all its functions with an ohm meter, looks fairly new and works fine.

Here are some pics of the board....