speedometer not working
LS/MFT
Joined: Jun 2000
Posts: 5,874
Likes: 0
From: Cary IL
St. Jude Donor '09-'10-'11-'12
Does the "service engine soon" indicator turn "on" while driving?
Yes: Need to diagnose problem in ECM based on code stored.
No: Does cruise control and/or radio speed compensated volume control operate normally?
Yes: Check for an open in CKT 817 between splice S244 and the central control module. (The wire from the vehicle speed sensor [back of transmission] and the CCM). If not, you'll need to replace the CCM, but before you do, let's check the CCM codes. That's easy with a '91. Let me know and I'll tell you how.
No: Will need to diagnose the VSS.
Let me know the findings then I'll direct you to the next steps.
Yes: Need to diagnose problem in ECM based on code stored.
No: Does cruise control and/or radio speed compensated volume control operate normally?
Yes: Check for an open in CKT 817 between splice S244 and the central control module. (The wire from the vehicle speed sensor [back of transmission] and the CCM). If not, you'll need to replace the CCM, but before you do, let's check the CCM codes. That's easy with a '91. Let me know and I'll tell you how.
No: Will need to diagnose the VSS.
Let me know the findings then I'll direct you to the next steps.
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4th Gear
Joined: Feb 2009
Posts: 4
Likes: 0
From: West Monroe LA
Speed Sensor
I had a similar problem in my 1990
The speed sensor was intermittent, also started stalling when I came to a stop, more like aengine would shut down.
I believe that throws a code when the sensor goes out.
Take a look at the codes with a scan tool
good luck
The speed sensor was intermittent, also started stalling when I came to a stop, more like aengine would shut down.
I believe that throws a code when the sensor goes out.
Take a look at the codes with a scan tool
good luck
