Tach issue LS1 swap in 88 Firebird
07-19-2017, 11:20 AM
#1
Registered User
Thread Starter
Join Date: Jul 2017
Location: Plainfield, IL
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Tach issue LS1 swap in 88 Firebird Hey guys, I need some help on my ls1 swapped 88 firebird. Im having troubles getting my tack to work. I have a 2002 "0411" pcm and an ls1 harness from pocket.
Ive already tried the pick up wire with a 680 ohm resistor with a fused switch to pin #10 and got nothing. Ive checked continuity on the cam wires to make sure I didn't nick anything putting the motor or wiring in and all came out good. I checked the voltage at Pin #10 on C2 of the PCM and got battery voltage, 12 when off around 14 when running. My scanner is showing rpm and the cam sensor is reading "high to low" and "low to high". I bought a Spek 2 1/16 tach gauge to put on my hood, wired it up... still no tach. The tach is also wired to pin #10 of C2.
Ive pretty much exhausted myself trying to figure it out, I really don't want to buy a tach adapter if I can get this to work. From what Ive read the tach adapters are hit or miss on if it will read right. And if i have to buy a tach adapter what would be the best option to go with?
Thanks in advance.
Ive already tried the pick up wire with a 680 ohm resistor with a fused switch to pin #10 and got nothing. Ive checked continuity on the cam wires to make sure I didn't nick anything putting the motor or wiring in and all came out good. I checked the voltage at Pin #10 on C2 of the PCM and got battery voltage, 12 when off around 14 when running. My scanner is showing rpm and the cam sensor is reading "high to low" and "low to high". I bought a Spek 2 1/16 tach gauge to put on my hood, wired it up... still no tach. The tach is also wired to pin #10 of C2.
Ive pretty much exhausted myself trying to figure it out, I really don't want to buy a tach adapter if I can get this to work. From what Ive read the tach adapters are hit or miss on if it will read right. And if i have to buy a tach adapter what would be the best option to go with?
Thanks in advance.
Last edited by Brandon Benes; 07-20-2017 at 01:46 PM. Reason: added info
07-25-2017, 12:34 PM
#2
Registered User
Thread Starter
Join Date: Jul 2017
Location: Plainfield, IL
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Update. The signal coming out my PCM works when not hooked up to my factory Tach. PIN 10 is getting power from both sides. Coming out of the PCM and wire going to tach is getting power as well.
Ive tried the Automerter 9117 and am still not getting Tach to work. With the adapter connected to both OE Tach and aftermarket tach, it zeros out. When only connected to aftermarket it works.
Any input is greatly appreciated
Ive tried the Automerter 9117 and am still not getting Tach to work. With the adapter connected to both OE Tach and aftermarket tach, it zeros out. When only connected to aftermarket it works.
Any input is greatly appreciated
Last edited by Brandon Benes; 07-25-2017 at 12:38 PM. Reason: added info
08-03-2017, 09:42 AM
#3
TECH Addict
I had my tach from my 1992 chevy pickup work fine with the ls/ pcm with no resistor. You probably need to change programming in pcm to work with your tach. I recently installed a suntec tach since stock only went to 5000 Rpms and it worked once I hooked it up same wiring as the stock tach.