96LT1Z

I just got my project up and running last week. Couple nights ago I sat in traffic with the car for a solid 30 minutes not moving much. When we finally started moving I noticed my speedo quit working. The first stop light there after the car died. Took it home parked it in the garage and noticed the rev lockout won't unlock. Replaced the transmission speed sensor this morning with no luck. ALSO noticed that the electric fans are always on when I start it. Also the Rpms dive between shifts when I drove it. I reset the battery and started it and it was normal for maybe a block and problems represented themselves. Would love some insight from you guys. Thanks!

stevo9389

You should have a check engine light if the fans are constantly running so go have it scanned for codes.

A friend of mine had a similar issue when he swapped to a TH400 (from a T56) without all the parts for the speed sensor so he left it unplugged. The car ran like crap under any kind of load (deceleration fuel cut off?) because the PCM always thought it was travelling 0 mph. We stuck it to either the side of the transmission pan or the floorboard (forget which one) and went from always reading 0 to something insane like 255 mph until he was able to get the speedo working with the transmission. I am not saying to do this and leave it that way but at least see if it helps.

96LT1Z

Well the car has heads, cam, intake, just haven't had it tuned yet. So i honestly don't know where to start

SS RRR

iTrader: (2)

Change PCM's?

96LT1Z

Nope didn't touch anything in the computer

SS RRR

iTrader: (2)

Follow the wires. Make sure they didn't get burnt somewhere.

93BlackZ28

iTrader: (5)

I agree with SS RRR, sounds like ground issue or burnt wire.

96LT1Z

I have a speedo again! The ground was bad on the passenger side of the block up above the starter.

96LT1Z

Replaced it last night and all is good!