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Discussion Starter · #1 ·
Hi, I have a 68 with XR7 tags. It has been on a rotisserie so everything was removed which included wiring. Lots of issues now. To begin with in the engine bay wires that go back to the tail lights they are fine. Above that is a three pin plug/pigtail. One pin has 12V I believe runs to the coil but the other two pins I thought might go to oil pressure and engine temperature gauges When I put a test light to them and turn the ignition on my test light pulses on the other two pins. I do not have the proper wiring for that particular plug/pigtail The wiring is a mess. I have had it running but oil and temp gauges do not work and front signals/markers do not work. I am in the process of pulling the dash out to see if I can identify the color of wires that go to that pigtail/plug and trace their origin. Due to age, paint overspray and difficulties in identifying wire colors---eg; red with yellow/or white or blue strip etc. I just cannot distinguish the colors on the wires that run through he firewall and to this plug/pigtail. Another problem is the wiring prints that I have are vague. Might someone be able to assist me?
 

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One pin has 12V I believe runs to the coil but the other two pins I thought might go to oil pressure and engine temperature gauges
You are correct, the flat 3 pin connector is for the coil, temperature and oil pressure sending units. The pinout is as follows:

CircuitColorDescription
16Red-GreenCoil
31White-RedTemperature
39Red-WhiteOil Pressure

Coach Jack
 

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Discussion Starter · #3 ·
Thank you very much. I now have to find out why the oil and temp wires are pulsing when ignition is turned on.
 

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Frog,

The oil pressure and temperature circuits ( and the fuel gauge for that matter )"pulsate" because they are fed by instrument voltage regulator. The IVR should pulsate at 5 volts. To test the gauges, you can BRIEFLY ground out the wire to either sending unit and the associated gauge should peg to the high side.

Coach Jack
 

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Hi, I have a 68 with XR7 tags. It has been on a rotisserie so everything was removed which included wiring. Lots of issues now. To begin with in the engine bay wires that go back to the tail lights they are fine. Above that is a three pin plug/pigtail. One pin has 12V I believe runs to the coil but the other two pins I thought might go to oil pressure and engine temperature gauges When I put a test light to them and turn the ignition on my test light pulses on the other two pins. I do not have the proper wiring for that particular plug/pigtail The wiring is a mess. I have had it running but oil and temp gauges do not work and front signals/markers do not work. I am in the process of pulling the dash out to see if I can identify the color of wires that go to that pigtail/plug and trace their origin. Due to age, paint overspray and difficulties in identifying wire colors---eg; red with yellow/or white or blue strip etc. I just cannot distinguish the colors on the wires that run through he firewall and to this plug/pigtail. Another problem is the wiring prints that I have are vague. Might someone be able to assist me?
I have been down this road. Not being a smart ass here. But I bought glasses a head mounted light and a magnifying glass and went from there. My 70 had a burnt up wire harness but its good now. Have you bought a jim Osborne Cougar manual
Very helpful
 

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Discussion Starter · #6 ·
Thank you again I will see if I can acquire the manual. I have remove the dash. the heater core was cracked and ruined a new rug with antifreeze. I have removed the heater- a/c assy. to replace the heater core and found only three of the five plastic pins with nuts that hold the right half dash in place were broken. The plastic is quite fragile. Anyway, I am moving forward and appreciate the help.
 

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I have been down this road with my 70 Cougar .new heater box. Wire harness , vacuum lines ignition switch engine harness......if I can fix this so can you
 

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So far as I know Jim Osborne has never offered a '68 XR-7 wiring manual. You can find many of the individual diagrams in the back pages of the Ford / Mercury factory shop manual. The free wiring diagrams at WCCC are available too but not too good.
 

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Thank you again I will see if I can acquire the manual. I have remove the dash. the heater core was cracked and ruined a new rug with antifreeze. I have removed the heater- a/c assy. to replace the heater core and found only three of the five plastic pins with nuts that hold the right half dash in place were broken. The plastic is quite fragile. Anyway, I am moving forward and appreciate the help.
For what it’s worth I was going to send out my main wiring harness to be checked out but what I ended up doing was clean the wires with carb cleaner so I see the colors I then got some tiny sand paper or ceramic cones that would fit inside all the connectors and cleaned them. The only problems I had after installation were bad grounds on the at front turn signals and back up lights
Hope this helps
 

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So far as I know Jim Osborne has never offered a '68 XR-7 wiring manual. You can find many of the individual diagrams in the back pages of the Ford / Mercury factory shop manual. The free wiring diagrams at WCCC are available too but not too good.
Strange....hit and miss years...I needed wiring diagram for 67 full size and nothing. 66 & 68 are available.....go figure...
 

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The complete 1968 XR7 wiring schematic is only found in the back of the Osborne Electrical Assembly Manual.
It is contains all the XR7-specific options in detail (and in tiny print). I wish these were printed full size.
These manuals are available for 1967 (AM0068) and 1968 (AM0073).
The shop manual does not include the XR7 ammeter schematic for either 1967 or 1968.


The 1967 XR7 wiring schematic is also documented in the 1967 Mercury TSB #45.
 
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