My sons Jeep is a 1979 CJ7. Just replaced his gauges now, and work fine now. Previous owner had too many wires attached to fuel gauge and fried it. Only 3 wires go to cluster. On fuel gauge, post farthest from temp gauge is pink wire. Red wire 12VDC Positive to post closest to temp gauge. "Red wire hot when ignition switch turned on". Purple wire with white tracer is to post on temp gauge fathest from pink wire previously mentioned. NO wires on buss bridge except for bridge itself.
Just a heads-up, what you refer to as a "ground bar" that connects the Fuel and Temp gauges is actually the complete opposite of ground. It carries approx. +5 volts. The CJ Fuel gauge includes a mechanical voltage regulator that knocks down 12 volts (which comes into the Fuel gauge on a red wire) to around 5 volts, and that strip you refer to as a ground bar actually carries +5 volts to the Temp gauge. Both the Temp and Fuel gauge take constant power, and use sending units that provide variable resistance from ground.
This is correct. I use a LM7805 for 5vdc to power the temp. Beware some gages are 12vdc.. Know what you are getting with a new temp never put 12vdc on it or it will be destroyed. I have seen ruined gages due to putting power on the wrong stud. The ground for the temp and fuel is the sending units themselves. The case of the Speedometer is grounded. Some lights require it. The metal strip is used for 5 volt from regulator to temp. More people don't get this. I have seen schematic wrong. it isn't a saturn 5. Thanks for this post
@@TelecasterRon Hi Ron. I have the same temp gauge issue. No 5 V to the temp gauge. While I can put together an LM7805 and hook it up I was wondering if you know who might offer the "voltage reducer strap" from the fuel gauge to the temp gauge?
Sir, just wanted to tell you that the buss between gauge is 12VDC positive. The wiring diagram for a CJ7 shows a red wire connecting to the positive post, but by the drawing, looks as if the red is ground. The ground to the fuel gauge is internal when the gauge is mounted to the cluster base. Don't ground the buss, just the cluster base itself as if it was mounted to dash. Fiberglass chassis? Run seperate ground to base.
Make sure the back of gas gauge is not touching the bare speedo casing. Use the cardboard from old guage or it will short out. I blew four 3 amp fuses before figuring it out. Cheers
Make sure cluster base is grounded. Change both gauges at same time with new gauges. if one goes bad, it will effect the other. Clean all insulator cardboards with electrical spray cleaner and let dry. Take your time and have fun! Double, triple check your work, wire correctly, hit the key and observe! If it's any thing like my son's CJ, the gauge shows just enough fuel to get to the gas station! LOL! Hope this helps people!
No, I have up. I believe i must have burned them out. I have long term plans to change the dash board to a hybrid of classic and modern with carbon fiber gauges so I just drive it. I only do short weekend drive and never off road.
+bestbitchable I had to replace mine, I just added a second gage below the dash/next to my second temp gage, When My tank is full the gage only reads half full when its near to empty it reads full, wires are crossed but I don't care I only have about 1000 in the jeep and shes a runner. I just calculate backwards I'm dyslexic so it helps:)
Hello, I did the change between my old fuel gauge, and put a new gauge from Omix ada, with a new sending unit, but the gauge is showing wrong, I think is something with the resistance, What can I do to resolve it?
The fuel tank send may need adjusting. seem like 10 ohm to 70 or something. Read the tank sending unit ohms. The resistance for the teml is read cold and hot again with the meter. Sending unit go bad and sometimes the wrong one has been installed. Look up the values for Emlty and Full and Cold and Hot online. You'll know quickly what the trouble is.
My sons Jeep is a 1979 CJ7. Just replaced his gauges now, and work fine now. Previous owner had too many wires attached to fuel gauge and fried it. Only 3 wires go to cluster. On fuel gauge, post farthest from temp gauge is pink wire. Red wire 12VDC Positive to post closest to temp gauge. "Red wire hot when ignition switch turned on". Purple wire with white tracer is to post on temp gauge fathest from pink wire previously mentioned. NO wires on buss bridge except for bridge itself.
Just a heads-up, what you refer to as a "ground bar" that connects the Fuel and Temp gauges is actually the complete opposite of ground. It carries approx. +5 volts. The CJ Fuel gauge includes a mechanical voltage regulator that knocks down 12 volts (which comes into the Fuel gauge on a red wire) to around 5 volts, and that strip you refer to as a ground bar actually carries +5 volts to the Temp gauge. Both the Temp and Fuel gauge take constant power, and use sending units that provide variable resistance from ground.
This is correct. I use a LM7805 for 5vdc to power the temp. Beware some gages are 12vdc.. Know what you are getting with a new temp never put 12vdc on it or it will be destroyed. I have seen ruined gages due to putting power on the wrong stud. The ground for the temp and fuel is the sending units themselves. The case of the Speedometer is grounded. Some lights require it. The metal strip is used for 5 volt from regulator to temp. More people don't get this. I have seen schematic wrong. it isn't a saturn 5. Thanks for this post
@@TelecasterRon Hi Ron. I have the same temp gauge issue. No 5 V to the temp gauge. While I can put together an LM7805 and hook it up I was wondering if you know who might offer the "voltage reducer strap" from the fuel gauge to the temp gauge?
Sir, just wanted to tell you that the buss between gauge is 12VDC positive. The wiring diagram for a CJ7 shows a red wire connecting to the positive post, but by the drawing, looks as if the red is ground. The ground to the fuel gauge is internal when the gauge is mounted to the cluster base. Don't ground the buss, just the cluster base itself as if it was mounted to dash. Fiberglass chassis? Run seperate ground to base.
Make sure the back of gas gauge is not touching the bare speedo casing. Use the cardboard from old guage or it will short out. I blew four 3 amp fuses before figuring it out. Cheers
Make sure cluster base is grounded. Change both gauges at same time with new gauges. if one goes bad, it will effect the other. Clean all insulator cardboards with electrical spray cleaner and let dry. Take your time and have fun! Double, triple check your work, wire correctly, hit the key and observe! If it's any thing like my son's CJ, the gauge shows just enough fuel to get to the gas station! LOL! Hope this helps people!
I had same prob I put thin layer of shrink wrap on backside of gauge to stop metal to metal contact
Thanks for the video and did you ever get the gauges to work?
No, I have up. I believe i must have burned them out. I have long term plans to change the dash board to a hybrid of classic and modern with carbon fiber gauges so I just drive it. I only do short weekend drive and never off road.
Need help replacing fuel gauge on 84 CJ7. 4.2 6 cyl. How to figure Ohms to know which gauge to get???
+bestbitchable I had to replace mine, I just added a second gage below the dash/next to my second temp gage, When My tank is full the gage only reads half full when its near to empty it reads full, wires are crossed but I don't care I only have about 1000 in the jeep and shes a runner. I just calculate backwards I'm dyslexic so it helps:)
Hello, I did the change between my old fuel gauge, and put a new gauge from Omix ada, with a new sending unit, but the gauge is showing wrong, I think is something with the resistance, What can I do to resolve it?
The fuel tank send may need adjusting. seem like 10 ohm to 70 or something. Read the tank sending unit ohms. The resistance for the teml is read cold and hot again with the meter. Sending unit go bad and sometimes the wrong one has been installed. Look up the values for Emlty and Full and Cold and Hot online. You'll know quickly what the trouble is.
those damn grease dampened gauges, i grounded the entire dash to the negative terminal.
Sorry the posts look backwards. start with my first post first. Thanks and "Keep Em Rolling"!