Speedometer only works once warmed up (Page 1/1) trivet APR 08, 11:59 AM Hi all, Took the GT out of storage for a wash and drive. Odd issue - the speedometer (odometer and trip odometer also) wasn't working at first. After she started to warm up, it started working, but very jerky. Then once she had been running for 10-15 minutes, the speedometer worked fine. Took her out again the next day, same issue. Tried searching for similar speedometer issues but can't locate anything. 87 GT with original 2.8 and auto transmission, 88,xxx miles. Thanks in advance for any help. Tim viperine APR 08, 12:18 PM I would start by checking the wires going to the VSS at the transmission, check for damage or proximity to the exhaust. Secondly, feel under the left side of the cluster for the wiring connector, make sure it is snug. You probably have to pull the 4-screw hush panel (7mm heads). Easy to access and start with. Mickey_Moose APR 08, 01:28 PM If you have a scan tool, you can see what the ECM is reading for a speed. If it is reading correctly, then the VSS and part of the wiring is ok - then check the C203 plug, the plug on the speedo (and wiring), lastly maybe a bad speedo If the ECM doesn't show you a speed, then you know it goes to the back (wiring or VSS). trivet APR 08, 03:47 PM No scan tool unfortunately - at least not for OBD 1