dash swap tach probs - Third Generation F-Body Message Boards

dellman83Z · 06-30-2009, 08:53 AM

I am just finishing up my 4th gen dash swap. Looks great, its from a 95 LT1.Problem I have is all the gauges work and are accurate except for the tach. It reads correct to 2500, then it has a seizure, most of the time it falls down to around 1000 or it spikes high to 5000. As soon as the motor gets below 2500 again, its accurate. I know its a v8 cluster and am not sure a dakota box will fix it. If anyone has some insight, it would be appreciated. Would it help to wire it direct from the gauge to the dizzy instead of using the old wire from the old cluster pigtail?

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johnny89345 · 07-01-2009, 04:08 AM

how hard was the swap also what custom work needed to be done

dellman83Z · 07-01-2009, 09:50 AM

It really was not that bad, some cutting, but a lot of wiring. That is what took the most time. The console wasn't that bad, but I have a megashifter, and that took a little fabbing to work. If you do a search for 4th gen dash swap, there are quite a few good threads for wiring, where to modify, and some pics.

Firebat · 07-01-2009, 01:14 PM

Try wiring it off the ignition coil or dizzy. I had a similar problem but it was vice versa - I had a 4thgen motor and a thirdgen dash with a bouncing tach.

dellman83Z · 07-01-2009, 01:29 PM

I gave that a try last night without luck. I think now I am going to add a ground strap to the motor, make a seprate ground for the black/white wire off the cluster and go to the block with that one also and see what that does.

Firebat · 07-01-2009, 02:32 PM

Do you also have the black wire from the cluster connected to ground? There are 2 grounds on the cluster, black wire and blk/wht wire.

dellman83Z · 07-01-2009, 02:37 PM

Yeah, that one too, and the red wire I think to a ground also, its that wierd one that in the wiring guide off another thread that needed to get grounded also. I know the cluster would not work without it.

Firebat · 07-01-2009, 02:41 PM

Here's some pinouts I found for both 95 LT1 Camaro and 95 LT1 Firebird Clusters:

Camaro-
http://shbox.com/1/95_z_cluster_pinout.jpg

Firebird -
http://shbox.com/1/95_ta_cluster_pinout.jpg

dellman83Z · 07-01-2009, 02:51 PM

That is in part the diagram I used to wire the cluster, heres a link to the other.http://www.thirdgen.org/techboard/at...od-wiring.gifA couple of the wires did not quite jive, so I used both to get it to work.

dellman83Z · 07-02-2009, 08:13 AM

I tried adding grounds, moved the orange wire to a battery lead, direct wiring, the only good result I got was that I separated the black and the black/white ground and made a new ground for each of them. Now the tach does not fall off until about 2800 rpm. I am really scratching my head at this that I cant figure it out.

dellman83Z · 07-25-2009, 04:17 PM

Update. I got the tach to work properly. Here's what I did for those out there that have the same problem. I added a msd 6al-2 box which I was going to do at some point anyways. One problem I found with my dizzy was that the condenser inside somehow got disconnected. I am not sure that fixing that would have solved the tach prob, but that is one thing to check for. After the new box was wired up, the tach also works properly. Coinsidentally, it runs better now with the new box.