RoDan

Ok guys, the tach was working before the motor swap now it does not function at all. The car starts and runs fine, no odd codes or anything and as far as I can tell the grounds are fine becaue if they weren't I doubt the motor would even fire. As far as I can tell all of the other electronics seem to be working, all of the gauges work so I do not know where to start...

Anyone ever have this issue?

RoDan

no one? I'm still stumped. All the wires seem to be in good shape comming off the PCM. I really don't want to have to pull the dash. I know someone else has had this issue before...

I'd appreciate any assistance!

RooRnZ28

iTrader: (14)

your put in a new motor.... did you install a new timing chain as well? That is where the pcm gets the signal for the tach, from the reluctor wheel attached to the chain.

way back, i swapped out my stock chain for a double roller and my tach wouldnt work afterward. After months of trying to figure it out, i replaced my double roller with an LS2 chain and the problem went away

RoDan

man I hope thats not it.... I can't see that being the issue because in HPTuners I get RPM. The new motor is an LS3 and it has the front cover cam sensor, and I used a double row timing set with the 2x reluctor, for LS2 style engines. Everything should work fine... Are you saying the dash tach ONLY gets its signal from the cam sensor? I figured it got its signal straight off the PCM, and if the PCM knew what RPM the engine was at it would just send a signal to the tach and tell it to display it.

I'm gonna go look for codes again specifically regarding cam sensor, and see if any new ones have cropped up.

RoDan

LS1s read the cam signal from the reluctor wheel on the back of the cam, where the distributor drive is. Engines with the cam sensor in the front cover read from the "high/low regions" on the cam sprocket. That is a picture of the n-motion I used, and I high-lited the reluctor regions. Is this not correct the correct sprocket to use?

I've also heard of people having issues with the wires being swapped in the front cover, could this cause a tach issue?... although if memory serves, it kept the car from even firing if the wires were backward.

RooRnZ28

iTrader: (14)

do you have any codes? I had a po343, which is camshaft signal stuck on high or something like that.. we plugged in autotap, and it could read the rpm's fine. the dash gauge was stuck on 0 though.. when we would start the car, it would hesitate before it would fire up, and the dash tach needle would move a bit, and fall right to 0 when the car would fire up

RoDan

that is EXACTLY what mine is doing, and the car is hard starting bad!

I went and rechecked the codes because I had that feeling, yep. I sure do have that p0343 code! I don't think it is the double row timing set though because it has the 2x reluctor on it, I'm thinking it is the cam sensor itself or the wires are backward in the harness....

I really do not want to have to change the timing set!!

Sales2@Texas-speed

iTrader: (5)

Have you tried swapping the outer two wires on that cam extension harness? MANY of them from Caspers are wired backwards right out of the package. You can swap the A and C wires down by the cam sensor or up by the rear of the intake where they plug into the OE harness (that is the easiest place to reach them). Try that, clear the code, and see if it helps!

RoDan

Matt, that fixed the problem! Thanks for your help, I appreciate it!

Man, how annoying is that? How come they can't get the wires correct in the first place?

Sales2@Texas-speed

iTrader: (5)

It's something about the harness being built as a cam EXTENSION harness for LS2 cars....and they're harness has them the other way from the LS1 car configuration. It just happens that they are always used to swap the Gen4 engines into early model cars instead of being used as an extension in a later model car...come to think of it, I don't think I've ever sold one to a customer with car that had a Gen4 engine from the factory.

Oh well....glad I could help!

helicoil

iTrader: (104)

Wow! My first search about my Newly found problem, no tach with LS2 swap into my 2000 SS and I also have the P0343 DTC. I 'll try to swap the A and C wires also, Although by the wire colors I would have thought to swap the center too as the factory LS1 sensor has a brwn/wht for the signal return and the Caspers harness has brwn/wht out on the end.

Anyway GREAT SITE! with info like this!

helicoil

iTrader: (104)

Son of a bit^h that was it! Thanks for the thread.

jermzz

iTrader: (18)

Sorry to being up an old thread.. but in whatg situation would a gen 4 motor car need a cam sensor extension? They should already have the cam sensor and facoty wire harness in the correct position.

what reason would an ls2 car need an ls2 extension harness with an ls2 motor? I'm confused. I'm putting an lsx 454 in my car right now, and I'm not sure what way to put the wires.

mine is from katech and made as a ls6 to ls2 adaptor so maybe its right?

NAVY99B4C

iTrader: (7)

I put the motor back in my car, i didnt change anything on the front of my motor but it is now hard starting and the tach will not work.

The car will start and idle fine but no tach and if i shut it off its hard starting again. Anyone know why this would be happening?

cornerburner

iTrader: (1)

Bringing this thread back as it seems to be a very common problem discussed on this forum. Unfortunately a problem that doesn't seem to be commonly resolved. As stated above about swapping the outer two wires, does anybody know if this is the case with the Racetronix cam sensor extension harness. I ask of course because I am having this very same problem with my setup.

Thanks

Psychopjv

iTrader: (16)

I've seen cam sensors go bad just from swapping a cam. In my case my double roller cam gear also decided to loosen itself causing this issue.

cornerburner

iTrader: (1)

Hmm... that's interesting. I sure have read a lot of these threads with the mention of cam gears loosening. I just cant quite imagine why that would be happening. I just built this engine from the ground up so I know for a fact that those cam gears are tight. I have a new cam sensor (the right sensor), the proper cam gear, and yet I still have this problem. After my last post I realized... duh, my cam extension harness is in fact a Casper harness. I got confused after having ordered extension harnesses from multiple vendors. Anyway, I plan to look into this wire swapping in the harness in the next few days here. I sure hope to find the answer like some of those earlier in this thread.