Vehicle: 2003 S-10 (4.3/4L60E) with a '99 5.3 Gen III and the original 4L60E.

So I got the S-10 up and running. With the engine off, key in the off position and trans in park. I am getting the dash lights lighting up for a few seconds, shutting off for a few seconds and then repeating. Also have a left indicator dash light that stays lit.

The neutral safety switch is also causing the truck not to start with the key. Put a jumper wire in and started right up. So, thinking that I will need a new neutral position switch at the trans. Correct or not?

Gauges: Temp gauge seems to be working (have not filled with coolant and brought to temp yet), No oil pressure movement (verified that the engine is bring up oil to the rockers visually, cover off), no gas gauge (I think this is related to the neutral safety plug being unplugged with a jumper wire in it) No Speedo (not plugged in, have to lengthen the wiring still).

In process of finishing the Y-pipe, so O2's are not plugged in yet. I'm sure that this code is being thrown (runs very rich).

Still working with the wiring guy on these, but need some other ideas on what to look for.

 

Anytime I get weird random electrical problems I start checking grounds. Lack of good grounds will make it do crazy things.

 

Thought I had this issue fixed, but it's back again. Up and running, but no gauge inputs. Water temp seems to be working, but nothing else. The dash lights up when the key is on, but no Tach, gas gauge, oil pressure. I did have this fixed at one point, idle is 750 rpm, oil pressure 45 lbs and 13.9 volts. Now back to the same issue.

Weird part is a back feed thru the system with the key in the off position. I'm getting random pulses that turn on the dash lights, leave the left blinker indicator on, then cycles to off and then repeats. Will kill the battery overnight. In the fuse box I get a relay that is also pulsing (clicking) off & on.

I'm leaning towards a grounding issue. There is a small ground attached to the upper bell house bolt (PITA to get to) that I had originally grounded to an aluminum head. Had gauges when moved to this location.

So could this be a bad body ground? (Metal mesh ground strap) Mine is bolted to the driver's side valve cover. Going to get a new HD unit and go from a trans bolt to the frame. I'll also recheck my small wire to see if that is not connected some how. Need to get this back on the road next week.

 

Valve cover MIGHT be an issue not grounding because the gasket is insulating the connection, and the center hold down bolts also insulated by the grommets. Just speculating here.....

 

Hey, anything is possible!

Did more research, going to pick up a new PRindl switch today. Reason: when I first tried to bring up the oil pressure, I had no power to the starter from the key switch. Jumped that connection and the truck rolled over fine. Later I pulled the jumper wire out of the connecter and reconnected the switch. Started fine.

Then the crazy dash lights, no crazy dash lights, back to the same issue.

Apparently, GM routes a lot of the interior power through this switch. So after 254,000 miles the switch might just be bad. Also still have an open ABS plug on the pass side that I forgot about. Last thing was I attempted to run the truck and put it into gear to verify the speedo. Nothing. Since the 4L60e is an electronic trans, this input must be needed to get proper function. I know that the trans is pumping fluid as there was a leak I had to fix.

So one more thing to add to the "list"

 

Replaced the neutral safety switch, old one was rough. Still the same. Then plugged in the headlights, no change.

Going to pull the battery and get to the grounds under there next. Block ground is fine. may pull some of the power wires to check the routing and possible grounding. Also going to pick up a multi-meter. What ever this is I did have the tach & gauges working before the sheet metal went on.

Frustrating

 

It almost sounds as if your hazard light circuit/flasher has infiltrated other circuits.

edit: I've had two square body chevy trucks that had stuck blinker indicators. Each time a new headlight switch fixed it.

 

well I'm lost.

Today I ran the voltage at the following:

Battery: 12.84
Alternator: 12.84
Fuse box:12.84

Pulled every connection, every ground

Still no change.

No gauges, random lights with key off. Starts and runs fine.

New harness, new neutral safety switch.

 

Stripped off the pass side fender to get a good look at the starter and grounds. Found a loose negative cable ground. So I added in a body ground, engine to frame and got everything tightened up. hooked up the battery, no change, still over loading at the B+ connection (fuse box). I still have full power at the battery, alternator and fuse box.

I checked a '01 Silverado, should be .002-.05 volts. So why is mine still showing full voltage?

I'm thinking that the ignition module has failed.