Transmission issue

JOY WALKER

MEMBER
1999 LINCOLN TOWN CAR
4.6L
V8
RWD
AUTOMATIC
197,000 MILES

Transmission does not up-shift and O/D light flashes in dash panel. Replaced fuse and transmission worked good for a matter of hours. Then the fuse was blown again. Unplugged transmission selector switch (neutral safety switch), and replaced fuse. It blew. I ran an OBD2 scanner on the car and there is a lot of smog controls on that same circuit. My question is can I disconnect those components one at a time to see if they are the faulty circuit?

3 Replies

HMAC300

MECHANIC
48,601 POSTS

No because it will set a code if it is a transmission problem. Have a transmission professional do it. It may be what is called a can bus problem so you need a professional grade scanner to check it.

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Thursday, July 7th, 2016 AT 4:07 PM

JOY WALKER

MEMBER
2 POSTS

I tried that. I had a professional check it at the transmission shop and he said "replace the fuse and if it blows the fuse it is not the transmission".

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Thursday, July 7th, 2016 AT 4:51 PM

JIS001

MECHANIC
3,408 POSTS

Yes you can disconnect those components one at a time when checking for a short. It is best to do that if the fuse blows right away. If it only blows when the vehicle has been driven for a while then I would suspect a faulty wire. What happens once the vehicle warms up the wire loom gets softer and sags down more causing the wire to rub on the engine and blowing the fuse. You need to inspect the wiring harness loom to see where it has melted to cause that wire to short. You will most likely also see other wires starting to chaff also but not completely short out yet. Hope this help, but I would recommend you take it in to a shop that is better equipped for this type of problem.

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Thursday, July 7th, 2016 AT 6:57 PM