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Discussion Starter #1
I put a 67 XR-7 dash into a 68 standard using a 68 XR-7 harness.

My oil pressure gauge doesn't seem to work. When I turn on the car, the needle pegs. I didn't replace the oil pressure sender. Do I need to? When I put to voltmeter on the leads to the meter, I get a 12 volt pulse every few seconds. It's all most as if it were connected to the blinkers (which it definitely is not).

My fuel gauge also pegs to full. I haven't put a meter on that yet.

Also, I cannot seem to find the tach wire in the engine compartment even though I bought a XR-7 engine harness w/tach. It would go to the - coil, right?

I am pretty sure the ground is good. I hooked up the ground wire in the wiring harness to the dash and installed a block to chassis ground strap.

Any advise?
 

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if you still have the non xr7 sending units still in the engine then you will need to change them for the gauges.
the oil light is just a pressure switch on the motor oil gallay.
you will need to change it out to the bell shaped one for the oil gauge to work.
if you were to start the car the gauge would have gone to zero when the switch opened up from oil pressure.

pull the wire off the sender and see if it will go to zero.

tach wire is part of the harness the runs to the ignition circuit behind the dash.
the stock tach does not hook up at the coil but plugs in at the dash harness to complete the ignition circuit, the car will not start without the tach hooked up unless there is a jumper installed in the tach harness.

not sure on your gas gauge but pull the plug at the tank it should go to zero if not then the wire going to the gauge has been grounded some where. (pinched in something , screw drilled through it, chaffed or cut wire touching ground ,)

the gauge will have voltage at the terminals at all times and will pulse as you said due to the voltage regulator on the gauge package.
gauges are pulled to ground by the varible resistors in the sending units that vary the current through the gauge windings.

are you changing out the complete harness to the car or just the dash.?
i beleve that you will need some of the under hood components as well like for the alt/amp gauge wiring.

if i am wrong i am sure some one will correct me .....it has been awhile since i messed with swapping harnesses.

p.s. don't forget to change out the coolant sensor......to the xr-7 type.
 

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Discussion Starter #3
Thanks for the info. I appreciate it.

I can't seem to find an XR-7 coolant sensor. There only seems to be one type.
 

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Since both Standard and XR7 came with the Temperature gauge I believe they use the same sending unit. The Oil Pressure sender will be different since the Standard has a light & the XR7 has a gauge.
 

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Discussion Starter #5
Bob:

Don said you may be able to shed some light on how the tach gets it's signal. I bought a XR-7 engine harness w/tach, but I see no wires going to the minus side of the coil. I always thought that is where tachs got their pulse.
 

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Dave, The tach is in series with the power supply to the coil. The XR7 starts out as a different body when the vehicle is bucked because there are so many differences in the two cars. You will need to replace the entire wiring harness under the hood to make the gauges work. The ammeter in your XR7 dash is now almost certainly also fried. You may also find that you have charging problems as the connection to the alternator and voltage regulator are different. To get the rest of the XR7 stuff to work you have to replace the rest of the body wiring harnesses. You might want to check with WCCC and see what a B grade set of XR7 harness run, and pick up the over head console, and roof mounting hardware, at the same time. If you wan tht elow fuel light to work, you need to get ECI Bob's Electroninc Low Fuel kit, as it will work with the current, non XR7 sending unit. For the Ammeter, you might as well go with the RCI voltmeter to replace what you have.

I know people hate to hear this, but the best way to get an XR7 dash is by buying an XR7. Sorry about the bad news.
 

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Yep to what Bill said.
The tach signal goes to the positive side of the coil via the ignition circuit.
In a nutshell: Ignition switch into tach, out of tach to + side of coil through the 'pink' resistor wire and engine harness.
 
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