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Speedometer only works once warmed up by trivet
Started on: 04-08-2019 11:59 AM
Replies: 3 (125 views)
Last post by: trivet on 04-08-2019 03:47 PM
trivet
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Report this Post04-08-2019 11:59 AM Click Here to See the Profile for trivetSend a Private Message to trivetEdit/Delete MessageReply w/QuoteDirect Link to This Post
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
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viperine
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Report this Post04-08-2019 12:18 PM Click Here to See the Profile for viperineSend a Private Message to viperineEdit/Delete MessageReply w/QuoteDirect Link to This Post
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.
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Mickey_Moose
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Report this Post04-08-2019 01:28 PM Click Here to See the Profile for Mickey_MooseClick Here to visit Mickey_Moose's HomePageSend a Private Message to Mickey_MooseEdit/Delete MessageReply w/QuoteDirect Link to This Post
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).
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trivet
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Report this Post04-08-2019 03:47 PM Click Here to See the Profile for trivetSend a Private Message to trivetEdit/Delete MessageReply w/QuoteDirect Link to This Post
No scan tool unfortunately - at least not for OBD 1
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