O.K. Guys-

Yesterday was a good day for diagnostics. Hooked up my new vacuum gauge and walla!!! Gauge tells me I have a leak at the manifold. So I check the upper manifold torx/allen bolts and they are all loose! I just put this crap together…how could it already be loose! Anyway, I tightened all to 25 lbs.

Now, the vacuum gauge is hovering around 15 lbs. And spikes once in awhile. The gauge says late timing or something like that. Anyway, I ran out of starter fluid to spray around for leaks, so I stopped that.

Tried to set minimum air, idle, timing. Once the car threw a 42,24 code which says my (est) is grounded or shorted open. I cleared the codes and they will not reset.

Besides the vacuum situation, These two things are happening also:
1. primary fan will not come on when it is supposed to. (I confirmed the fan motor/relays/fusable links are good.
2. The gauge for volts on the dash is hovering like at 9 volts. It always read near 13. My scanner shows 11.4 volts at battery. I have had the following checked and they check good: battery/altern/ign. Module.

I think maybe the volt gauge and primary fan might be on the same circuit. When you load on accessories, ie: ac/headlights/blinkers, the volts drop on the dash gauge to around 8 volts. But the headlights do not dim.

Timing light and scanner show timing advance with est hooked up, so I think that is o.k., but I could not get my probe light to come on when I probed the est connector on both sides while motor ran. Shouldn’t it have power in there?, but the car is advancing it’s timing.


I DROVE IT AROUND THE BLOCK!!!!! It did not backfire or have excessive valve train noise. (remember I put in a lt4 cam/1:6 rollers.)

So, let’s all become electricians and trouble shoot the fan/gauge.

Anyone have the wiring diagrams for the dual fan set up and the diagram for the volt gauge?

Also wiggled the plugs at the ecm and pulled wires there, tapped on ecm while motor ran…no change.Fuse is good at fuse block for fan circuit. I have 12 volt source key on behind fuse, just no 12 volt under the hood for fans. I think I have a short causing the dash gauge to read real low.

Keep in mind this is a garaged always low mile, non beater. 70k orig. miles.

Could in proper rocker adjustment cause the low vacuum?, but can the volt problem be associated with the vacuum problem?

 

I have learned the hard way to torque the intake, wait 24 hrs then go back and remove the bolts one at a time and install the thread sealer and retorque. Remove the power from the ECM for 30 sec either at the pigtail or fuse panel. Jump the ALDL connector for code retrieval and turn on the key. The fan SHOULD come on during retrieval as a self test. If it does it rules out the ECM driver and the relay/wiring. If it doesn't, then start looking at fuses or the links near the starter junction. The generator has a fuse link at it's output between the batt and the gen. The plug at the gen should have 12 volts on BOTH pins with it unplugged from the gen and the key in the on position-engine off. More info might help, any wiring changes made?

 

Danno-

I have followed some of your past posts regarding alties yesterday....and walla!!! found my problems all except the 15 lbs. of vacum at the manifold.

1 bad fuse at FAN/CCH or something.
1 cut signal wire (brown) of back of alty.

Your clear test directions got me out of that one

Thanks again Danno!!!!!!!