'87 T-bird dashboard error message

I've got an '87 T-bird with the digital dashboard.
A couple times recently, the fuel display that normally shows the gallons of fuel remaining displays "CO". While this is going on, the DTE
(Distance To Empty) display is inaccurate (500-600+ miles, (I wish)).
This has happened twice. It continued for a few days each time (half a dozen engine starts/stops), then it behaves normally.
I'm assuming this has something to do with the gas tank float, but I'd like to nail a diagnosis down a bit better before I start yanking stuff out.
My dad thinks the float is just sticking, I don't think so, if it were sticking, why would it not just hold the same level for a while.
Other possibility is a bad connection somewhere between the dash and the sending unit, but I don't know where.
Anybody got any ideas? Or a pointer to a web page that'll tell me what the "CO" means?
Thanks, Mark
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Mark Mitchell wrote:

"Circuit Open"
I'll guess it usually happens after a fill-up. Probably not stuck, just faulty.
Rob
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Hi Mark,
I've got an '87 T-bird turbo coupe and this is quoted from my '87 ford factory shop manual (Chassis & Electrical volume B). Hope this helps.....
TEST TG CO DISPLAYED, ANALOG FUEL GAUGE CAN NOT BE CALLED UP -------------------------------------------------------------------- TEST STEP RESULT ->ACTION TO TAKE -------------------------------------------------------------------- TG0 VERIFY CONDITION CO displayed ->GO to TG1. -------------------------------------------------------------------- TG1 CHECK FUEL SENDER WIRING AT SENDER
+Disconnect groud cable to battery. +Lower fuel tank to gain access to fuel sender connector. +Unplug fuel sender connector. +Jumper variable resistance terminal and ground terminal of harness together. +Reconnect battery. +Tun ignition key from OFF to RUN. +Check digital fuel display for CO or CS. Note: it may take several minutes for the gauge to respond.
CO displayed ->GO to TG3.
CS displayed ->GO to TG2. REMOVE jumper. --------------------------------------------------------------------- TG2 CHECK SENDER
+Turn ignition key to OFF. +Measure the resistance of the fuel sender at the sender terminals. +Verify that the resistance is between 9 and 161 ohms.
OK ->INSPECT fuel sender wiring connector female terminals for flash or loose fit. SERVICE as required.
NOT OK ->REPLACE sender. -------------------------------------------------------------------- TG3 CHECK FUEL SENDER WIRING AT CLUSTER
+Disconnect ground cable to battery. +Remove cluster and secure connectors from shorting. +Jumper variable resistance terminal and ground terminal of harness together at sender. +Verify continuity between Pins 12A and 13A of cluster connector.
OK ->REPLACE tach/ multigauge module.
NOT OK ->SERVICE fuel sender wiring for open circuit. --------------------------------------------------------------------
Bill
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