Mark Mitchell

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

 

trainfan1

Mark Mitchell wrote:
> 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

"Circuit Open"

I'll guess it usually happens after a fill-up. Probably not stuck, just
faulty.

Rob

BILL

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