Starter Relay

[DicksDodge]

I'm not one to bring up old posts, but this is related to my truck. I went to start the truck last weekend (70 W200) and it started, died (no choke, so this is normal) but when I tried to restart it, it just clicked. I check under the truck and found the positive cable from the starter relay to the starter is baked, all of the insulation is cooked off. Also the small wire is baked as well. Apparently it was touching my e-brake cable housing because it got so hot it melted the cable and slightly tack-welded the housing to the steering box. Thinking it was a bad cable, I replaced the cable from the relay to the starter and the smaller wire (10-gauge). There is also another wire on this post that has an inline fuse. The upstream side of the fuse got hot, but it looks like it is a result of the heat from the other wires because it did not burn the fuse so cut off the connector to good wire and replaced it with fresh wire. Also, while I was at it, I added a ground from the front left side of the block (yes, I sanded it to get good metal) to the chassis (also sanded). When I tried to replace the negative on the battery, it arced terribly. No go on that. The strange thing (among other things) is that when I check across the pos and neg on the battery I get power (test light) but when I try to use either end of the new ground cable, or the existing block ground that goes to the battery, I don't get a ground.

Any thoughts?

[hmaynord]

When I tried to replace the negative on the battery, it arced terribly. No go on that. The strange thing (among other things) is that when I check across the pos and neg on the battery I get power (test light) but when I try to use either end of the new ground cable, or the existing block ground that goes to the battery, I don't get a ground.

Any thoughts?

I'd try another cable from negative battery to the existing block ground. wonder if that arc did something to it internally.
when you say, "no go on that," you mean you've got no power in the vehicle anywhere?

[DicksDodge]

Right now I have no power to the vehicle. That is only because the negative cable is not connected. If I use the negative on the battery as a ground and touch the test light to the positive on the starter relay it lights up. I spoke to a friend of mine this morning who is a big Mopar guy, he says the smaller line on the starter relay should not be constantly hot. I am not sure if that would cause everything to ground out unless the grounding melted the inside of the relay. Just for information I did have the starter tested yesterday and it tested fine.

[hmaynord]

I don't think I'm picturing correctly the tests you made.
That #10 wire from the other terminal on the relay is hot only when ignition switch is in start.
I would try a remote starter switch, but I don't remember how to hook it up.

[Wildergarten]

From the description, it sounds like the line from the relay shorted first when you tried to start it, and may have fried the relay internally. First I'd disconnect the battery entirely and everything on the relay and use a continuity test to see if the stud of the relay or the terminal to the solenoid is shorted to ground with nothing connected to them. That way, you'll know if the problem is now your relay in addition to wiring. If that's good, then replace any fried wire and be sure to check the connections at the ignition switch.

From there you can bring up systems from the battery toward the rest of the truck. The goal here is to be sure you didn't fry something inside the harness to the ignition switch (for example, the line from the battery to the alternator gauge, through the ignition switch, and back to a shorted relay, as the power can take all sorts of strange paths in funky old wiring). After a continuity test to see if there is a short between the line from the relay through the firewall and ground I'd first connect that main supply wire from the rest of the truck to the relay without the battery connected to the stud and touch a clip lead from the battery to the stud. If all is quiet, clip it on and go to the ignition switch to look for 12V. If you've got that, I'd play with the jumper to bypass the switch to see if each system comes up OK, all of it still supplied by that clip lead from the battery to the stud. Effectively, the clip lead limits the available current from the battery so that you can test each system without enough available current to fry something.

etc. That's all I have time for.

[hmaynord]

finally, an answer that makes some sense

[Wildergarten]

finally, an answer that makes some sense

I'm assuming you mean mine. Chasing down an electrical problem in an antique wooden boat sitting in salt water teaches a lot about how many things can go wrong and how to dig out. Take all the problems one would find in an old truck, add salt, and then a maze of ground wire connection problems. It was a good education, but I never want to do that again.