ck90211

Need help on locating the engine speed sensor that sends signals to the tachometer. Just installed a salvage engine into a 96, and everything working great, except tachometer not responding. Before I pull out the instrument cluster to diagnose, perhaps it would be a good idea to make sure this engine speed sensor is plugged in right (or functioning).

Thanks in advance.

williamb82

the tach signal comes from the ignitor. if it wasnt plugged in then the engine would be running like crap. there are 2. 1 for each cylinder bank. so its either a wiring problem or the tach is bad. if the tach worked before id check every connector on the engine harness asuming you used your old harness. if you used the one that came with the engine could be a bad wire.

ck90211

Thanks Williamb82, it was working before. And yes about engine running crap if there weren't any engine speed signals. Will get multimeter out to diagnose/find bad wires.

Added: After a longer drive tachometer is alive again. Probably a less-than-good connection somewhere when putting the engine back in.

williamb82

yeah, prolly just have a plug that had a bad connection due to too much dielectric grease in it or something. at least you didnt have to go chasing wires. that can be fun. lol. heres what my 84 looked like when i built the engine harness for my megasquirt 2.

http://www.cardomain.com/ride/2042690/18

3UZFTE

Does the Tach signal come from the cam position sensors?

williamb82

no. ignitor. or if for some reason your wanting to install an aftermarket tach you can grab te signal from the neg side of either coil. just make sure that your tach is set for a 4 cyl, not an 8 cyl. each ignitor/coil is running half the engine only.

williamb82

lol. didnt know you had an ls. just got mine a few weeks ago. still sorting some issues out. needed a new daily so figured id get a 1st gen ls400 and ride in style and comfort. and the bigger rods incase this car gets the turbo bug too!