So I've got an 85 Elco that I've just been tearing my hair out trying to get the gauges to work. To start, the temp gauge hardly moves at all but it does move. The fuel gauge stays at full, will move down about an 8th of a tank and then just sit there. Voltmeter and oil pressure work fine.
Had to replace my temp sending unit and when I did, the gauge stopped working. I've bench tested the sending unit, made sure that when i installed it I took off all that sealant to make sure the connection was good and no dice. Gauge reads low temp and when the car gets up to temp, the needle hardly moves. Computer reads temp properly, not having the thermostat stuck open or anything. I ended up wanting my gauges tested and rebuilt and some new needles put on so I took them out of the dash, had them worked on when I brought them home i bench tested them to make sure they worked properly. Using a potentiometer and the proper values from my shop manual I made sure the gauges worked perfect and they did. Put everything back in my car and nothing. They still behaved the same.
Was having issues around this time with my fuel pump so I changed the sending unit while I was at it and still no change. I checked the wiring, no added resistance or anything, didnt just check for continutiy. Moving back to my temp gauge I decided to check the connector and it did add some resistance, about 50 ohms so I replaced the connector and tested it again to find all was good and well. Gauges still behaved exactly the same.
Thought I might replace the printed circuit board on the back of the dash so I did. No improvement. I took every single connector that interfaces with the printed circuit board and cleaned everything. Cleaned all the contacts on the back of the gauges too. Cleaned all of the connectors in the plug that interfaces with the printed circuit board. It's as if I didn't make any changes, the gauges kept doing what they were doing.
At this point I'd had it and my car was getting parked because the cat got clogged so I decided to hell with it, I'm tearing the entire dash out to do some other things I've been wanting to fix. I checked all the wiring behind it, checked the fuse block took it apart and cleaned everything. Once I got everythign sorted behind the dash, made sure the wiring was good from the plug to the firewall and beyond, checked and cleaned and made sure every single ground in the cabin had a good connection with clean metal I buttoned everything back up, replaced the dash and reinstalled the gauges. Absolutely no change.
I then went into the engine bay and went through every single ground strap, tested all of them and then cleaned them, making sure I had good metal to metal contact. Still absolutely no improvement.
I feel like I'm missing something so stupidly simple it's going to make the rest of my hair go white when I find whats wrong. My sending units bench test fine, the gauges bench test fine even when in the dash pad and I'm hooking up alligator clips to the interface for the printed circuit board, but when installed int he car they just don't work properly. They arent pinned at max or minimum and if I take the sending unit wires and short them to ground, they max out. Can anyone think of something I'm missing? I've got about 6 months working on this off and on and I am completely at a loss. The big f u is that everything was working perfectly fine at one time until the temp sending unit quit and I decided to have my gauges worked on. I even took the gauges back to the shop that worked on them and we tested them and they worked just fine. Thanks for any insight some of you may have.
Had to replace my temp sending unit and when I did, the gauge stopped working. I've bench tested the sending unit, made sure that when i installed it I took off all that sealant to make sure the connection was good and no dice. Gauge reads low temp and when the car gets up to temp, the needle hardly moves. Computer reads temp properly, not having the thermostat stuck open or anything. I ended up wanting my gauges tested and rebuilt and some new needles put on so I took them out of the dash, had them worked on when I brought them home i bench tested them to make sure they worked properly. Using a potentiometer and the proper values from my shop manual I made sure the gauges worked perfect and they did. Put everything back in my car and nothing. They still behaved the same.
Was having issues around this time with my fuel pump so I changed the sending unit while I was at it and still no change. I checked the wiring, no added resistance or anything, didnt just check for continutiy. Moving back to my temp gauge I decided to check the connector and it did add some resistance, about 50 ohms so I replaced the connector and tested it again to find all was good and well. Gauges still behaved exactly the same.
Thought I might replace the printed circuit board on the back of the dash so I did. No improvement. I took every single connector that interfaces with the printed circuit board and cleaned everything. Cleaned all the contacts on the back of the gauges too. Cleaned all of the connectors in the plug that interfaces with the printed circuit board. It's as if I didn't make any changes, the gauges kept doing what they were doing.
At this point I'd had it and my car was getting parked because the cat got clogged so I decided to hell with it, I'm tearing the entire dash out to do some other things I've been wanting to fix. I checked all the wiring behind it, checked the fuse block took it apart and cleaned everything. Once I got everythign sorted behind the dash, made sure the wiring was good from the plug to the firewall and beyond, checked and cleaned and made sure every single ground in the cabin had a good connection with clean metal I buttoned everything back up, replaced the dash and reinstalled the gauges. Absolutely no change.
I then went into the engine bay and went through every single ground strap, tested all of them and then cleaned them, making sure I had good metal to metal contact. Still absolutely no improvement.
I feel like I'm missing something so stupidly simple it's going to make the rest of my hair go white when I find whats wrong. My sending units bench test fine, the gauges bench test fine even when in the dash pad and I'm hooking up alligator clips to the interface for the printed circuit board, but when installed int he car they just don't work properly. They arent pinned at max or minimum and if I take the sending unit wires and short them to ground, they max out. Can anyone think of something I'm missing? I've got about 6 months working on this off and on and I am completely at a loss. The big f u is that everything was working perfectly fine at one time until the temp sending unit quit and I decided to have my gauges worked on. I even took the gauges back to the shop that worked on them and we tested them and they worked just fine. Thanks for any insight some of you may have.
