Honee08

The fuse blows as soon as the key is turned to run position just one click over. I put a test light on the socket to the fuse and opened the key and test light turns on indicating a short. Now I started pulling fuses to try and get the test light to de illuminate and pulling the 50 amp IGN fuse under the hood made the light go out. No other fuse made the light go out when pulled. I have the hanes manual but it doesn't go into specifics about what this 50 amp fuse is powering. Willing to pay for some advice anyone!

GaryDoug

Factory manual for 98: http://www.mediafire.com/file/qzbtnv...arked.pdf/file

The Gauges fuse circuit is on page 8-329

One of the sections shown on that page is for the BTSI, which is on page 2-55 in the steering column section.

peterpar

I'm not sure what you're describing doing here? Are you testing across both the terminals of the #9 fuse with the fuse removed, the ignition switch in run position and the test light lights? If this is the case, the bulb in test light has taken the place of the fuse and it consumes the power of the circuit at the test light instead of blowing the fuse because all the wiring opposite from the battery source has become a negative potential by allowing a ground path through the coils of the relays in the circuit.

The 50 amp ignition fuse provides power to the #9 gauge fuse through the ignition switch contacts when the switch is turn to the run position. The #9 fuse is blowing because there is a direct short to ground somewhere after this fuse. One of the coils of a module could have shorted out, blowing the fuse. Try isolating or unplugging the modules one at a time to see if that clears the problem.

Honee08

Hello everyone I have pulled every module that I can see without pulling the dash. Bcm, ignition switch, lighting control, and cruise control, stereo deck, and both break switches. The fuse still blows with any of these unplugged and at one point all were unplugged and the fuse was still blowing. I even pulled the alternator wires off last night and still blowing the fuse but I didn't make it to the starter cause the mosquitos were swarming me. Anyway I think it is a direct short to ground what makes me more certain is how the fuse explodes not just pop so it has to be a hefty wire shorting. As far as the test light I had the 2 sockets of the #9 fuse in front of me one has a small screw drilled in with the test light clamp and the other end had the point of the test light.

Honee08

I also pulled the cluster and not suprising the fuse still blew when I opened the key. I have visually inspected most of the wiring and some of the wiring was still wrapped in the plastic tubing and "looked" undisturbed. Where I am at now is physically chasing the wire coming out of the fuse block from fuse #9 and trying to follow the wire that doesn't have power when the key is turned. Is there a better procedure for the process of elimination using the test light and pulling fuses?

peterpar

[The fuse and wire gauge of the circuit are sized to be able to carry the amperage load of the equipment it powers. Anytime a positive wire comes in contact with a direct connection to a ground, the fuse will as you say "explode" because of the high amperage draw it creates. Regardless of wire size, you should be only looking at the wires that are part of the #9 gauge fuse circuit. If you have unplugged all devices shown on the drawing Gary (page 8-329 of the 98 service manual) lists above and the fuse still blows, you need to visually check the pink between the fuse block and all the connectors for any bare wire spots or pinches that could allow the circuit to go to ground. I've attached a pdf of that drawing. With everything unplugged and the fuse blowing, this should have isolated the problem to this wire because that is all that is left of the circuit.

Testing the terminals of fuse block like you describe is not a test for a short, it shows you have voltage at the two terminals. Like I explained above, you're probably reading through the windings of the relay coils in the circuit so one terminal of the fuse (from the ignition switch) is a positive potential and the other is a negative potential which will energize the test light. To check for a short to ground, you need to test with the fuse removed using a meter set on Ohms or continuity tester between the terminal not coming from the switch and a body ground to see if there is continuity. If all the connectors in the circuit are unplugged and there is continuity, this would show the wire has come in contact with a ground and you'll have to trace the pink wire until you find the point of contact.
I also should mention that it is a bad idea to use something like a screw in the fuse block terminal as you described. It could damage the fuse block terminal so that it doesn't contact the fuse when installed. Try using something like a bent paperclip in the clamp of the test light to probe the terminal.

Injuneer

Honee08

Found it! It was the wires going into the Daytime running lights module.

Honee08

"Peterpar" tell me where to send the check brother.

peterpar

No need for that. You are the one that found the problem. I was just trying to direct you to look in the right areas. I can't tell from the pictures, what actually happened. Did a wire short out or was the module bad? Some of the wires going into the connector look like they been hot, but several others look like they may have contacted a ground.

GaryDoug

Being a Chevy, all the power to the headlights goes through that module in some low-light conditions. Carries a lot of current, especially if the high beams are selected. You should be able to just unplug it.