Instant MPG reads "0"
Thread Starter
3rd Gear
Joined: Sep 2003
Posts: 3
Likes: 0
From: redwood city ca
Re: Instant MPG reads "0" (SunCr)
Is there anything to check without a reader. ( don't have one now, but could if I HAVE to).
Where's the sender for "fuel used" ?? Can I trace the wire to it??
By the way thanks for your help !!!
Joseph
Where's the sender for "fuel used" ?? Can I trace the wire to it??
By the way thanks for your help !!!
Joseph
Team Owner
Joined: Nov 2000
Posts: 45,085
Likes: 1
From: I was a young troubadour when I rode in on a song, and I'll be an old troubadour when I'm gone.
St. Jude Donor '08
Re: Instant MPG reads "0" (gazelle)
There isn't a 'sender' for the fuel calculation. The ECM itself figures the fuel usage. Sounds like something else is amiss.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Instant MPG reads "0" (JADVette94)
Sorry, don't have info on your '94, but it may be similiar. The digital cluster communicates with the ECM on the serial data line sending fuel level and speed info and getting the instant and/or avg data back for display. It's a bi-directional circuit which is spliced to the diagnostic connector and read at Pin E for all OBD1 GM vehicles. This is the circuit that communicates ECM data to a scanner. The only way I know to test it is to plug in a scanner and see if there is communication with the ECM. If not, the wire or the ECM is bad, though the PROM could be bad too. If it will communicate data, then something is wrong from the splice to the cluster or the cluster is bad. Absent a scanner, you can ground the diagnostic connector and see if will flash a code 12. You should also verify that there is a Check
Engine Light with the key on, engine off. If either condition exists, and the MPG is zero, the wire or the ECM is probably the culprit. With an intermittent, though, I'd check connections along with the integrity of the wire before suspecting the ECM.
Engine Light with the key on, engine off. If either condition exists, and the MPG is zero, the wire or the ECM is probably the culprit. With an intermittent, though, I'd check connections along with the integrity of the wire before suspecting the ECM.
