View Full Version : Coupe GPS gauge set wiring
BigShooter
08-20-2022, 08:14 PM
Hey all - need some help on gauge wiring for Coupe GPS set. The GPS gauges come with their own wires for oil pressure and water temp, which have the proper plugs on the ends to connect to the sensors - I'm assuming I need to use these official wires.
However, can anyone verify that for me? Then what do I do with the FFR 'sending unit' wire harness wires (there is 6 - 3 grounds and oil pressure, oil temp and water temp.) - can the FFR wires be used with the GPS gauge plugs??
edwardb
08-20-2022, 11:33 PM
Yes, use the wires that came with the gauges to attach to the sensors. You can either home run those wires directly to the gauges. Or you can attach them to the respective Ron Francis sending unit wires. That puts the signals through the large dash connectors making it easier to disconnect everything if necessary. I prefer the latter and have done it that way on my builds.
BigShooter
08-21-2022, 03:09 PM
that makes sense. I also like the idea of using the large dash connectors - however, the Ron Francis harness only has an oil pressure positive and ground, but the GPS gauge for oil pressure has 3 wires - do you remember what the third is for?
Thanks again for all the feedback!
that makes sense. I also like the idea of using the large dash connectors - however, the Ron Francis harness only has an oil pressure positive and ground, but the GPS gauge for oil pressure has 3 wires - do you remember what the third is for?
Thanks again for all the feedback!
The gauges should have come with specific instructions from SpeedHut (if that's the manufacturer of your gauges). Those instructions should identify what every gauge wire is for.
https://thefactoryfiveforum.com/attachment.php?attachmentid=171369&d=1661113171
edwardb
08-21-2022, 09:12 PM
that makes sense. I also like the idea of using the large dash connectors - however, the Ron Francis harness only has an oil pressure positive and ground, but the GPS gauge for oil pressure has 3 wires - do you remember what the third is for? Thanks again for all the feedback!
That's a change from Speedhut. Previous oil pressure sending units from Speedhut for a number of years (and all that I've installed) are 2-wire resistive style units. Now they've gone to a voltage output style sending unit which needs the third 5-volt reference wire. The Ron Francis harness and Speedhut provided instructions it seems haven't caught up with this change. Your simplest solution would be to use the supplied Speedhut cable. It has the proper connectors on each end for the sending unit and the gauge. These instructions from Speedhut's website show the 3-wire connection to the gauge. https://speedhut.com/content/instructions/2in_and_258in_revolution.pdf
Note to Factory Five and Speedhut: This has been a repetitive question/issue for a couple years now!!! The 3-wire sensor is apparently an upgrade from the previous (and troublesome) 2-wire sensor. Need to update the manual, harness, and instructions accordingly.
BigShooter
08-23-2022, 11:14 PM
I did hear back from Dan at Factory five on this too, and for the GPS gauges he recommends using the GPS gauge wire for the oil pressure since it already has the 3rd wire in it. The GPS gauges do come with instructions - which look like a combo of charts like Papa has shown above and also FFR instructions with a revision date of July 2007....hmmm.
With this helpful info from all y'all and piecing together scraps of outdated combined with current instructions I might just get this buggy on the road someday!! Edwardb - you are correct, there are many updates that are still needed on these manuals....sigh...