The Summer of Ven: The Electrical Phantasmagoria of Murdervan

Here’s a surprise retropost for you! I actually blocked out this post about Murdervan from a template some time last August, before I sold the sitevan and bought a new one. I ended up never finishing it in lieu of updates about Spool Bus and quite a few robot events, because after all was said and done, Murdervan didn’t have much wrong with it. I put a few hundred miles on it just around town as a daily errand runner but with more curb jumping and casual non-roading – note I didn’t say “off-roading” for a reason, just going places that isn’t…. public paved roads. What, who’s gonna stop me?

By July, though, I noticed it had developed a habit of popping the fuse for auxiliary lighting. This meant no running lights, no dashboard lights, and so on. The horn was also involved, straightly enough. If I put new fuses in for either circuit, they’d go if I tried to turn on interior lights or …. use the horn.

What it told me was some ghostly electrical problem residing in the dashboard area, the kind of electrical problem that gets a lot of things junked, probably even more so today as cars depend highly on all sorts of electronics and software. Luckily, this thing is so paleo that it was probably shorted wires to ground somewhere, like from chafing or a previous overheating adventure that is only now manifesting. The only trouble is now finding where.

I’ve said frequently now that part of the upside of having a flock of misfit ven, especially a new cast member you dug out of someone’s yard, is that it helps alleviate the fear of “Well what if I can’t put it back together again?”. So what if I can’t? Murdervan was going to be a helpful lesson for any issues Vantruck might have in the future. So I just dug in and started removing all the dashboard panels and bezels to expose as much wiring as I could.

The usual aftermarket service manuals are pretty worthless for electrical systems, but at least they contain (usually several versions of) system diagrams with wire colors and general locations I could follow around. I started with the horn circuit, for example, which is a greenish-yellow wire. I found it in the steering column bundle and followed it outside the van through this bulkhead connector in front of the driver’s floor:

So by 1991, they turned what was just a big bundle through a body grommet (in Vantruck and Spool Bus) into an actual bulkhead connector. This is certainly an improvement!

I continued to follow the yellow-green wire around through the various harnesses until I confirmed that yeah, it just ended at the horns.

So…. What’s the deal? When the horns are used, presumably this wire is energized, and in doing so, bad happens. Very strange.

This is a view of the bundle that goes up to the steering column. The auxiliary lighting circuit, a blue-red wire, has a branch that goes up here too for dashboard lighting and the like.

Like any good and competent engineer, I started jumping fuses and put the whole van on one of my lab power supplies to give it a maximum of 15 amps into the various circuits. My goal was to feel around (absent having a FLIR camera on me) for what wires got hot as I held various switches and buttons down to energize the circuits.

This is a more legitimate method of finding shorts and high-resistance areas than you might think….provided you’re sane about it. I wasn’t, and with that 15 amps and non-judicious use of the horn switch, I started smelling terrible things.

Turns out I roasted the horn switch. Oops. The mystery still isn’t solved, but at least I’ve knocked one branch of it completely out of the picture.

As I continued to pump 15 amps now into the auxiliary lighting circuit, I felt the red-blue wire inside the bundle that went into the steering column get warmer. So the power supply feed to the steering column was acting up, and either it or the horn switch (in the process of giving the power to the horn circuit) was causing a short.

That means the steering wheel had to now come off. I actually bought a steering wheel puller a long time ago for Vantruck to correct it’s 15 degree “Left is Straight” error, but never used it because, again, I wasn’t in a good position to not be able to put it back together quickly.

Well now I don’t give a shit, so off the steering wheel comes! Under the steering wheel lies some slip rings and switches like the turn signal switch. Any one of those could be the source of the shorting problem.

I continued to dismantle the steering column as well, following the red-blue wire upwards. I noticed that it was grounded to the steering column at one end (that screw terminal in the middle) yet somehow also carried power. What?

More digging revealed that it wasn’t some kind of Ford Family of Fine Fuckups engineering choice to float the entire steering column at 12 volts, but that they just got lazy and used the same wiring color to go into this weird connector here that…. Hey, wait a minute.

I found out what this was: It’s the light bulb socket to light up the PRND69L transmission indicator. There is no light bulb in it. The contacts had for some reason melted together, and was Shorting the 12v auxiliary lighting feeder wire straight to ground through the steering column!

Well I found my villain there. Check out that burn mark where the whole thing heated up! Oddly enough, the contacts themselves were not damaged, just touching. I just pried apart the housing a little, back to its un-deformed shape, then stuffed in an obnoxiously bright T5-sized white LED bulb, and suddenly, all was fine.

I’m not going to ask questions about how this interacted with the horn circuit. The only possibility I can think of is, this auxiliary circuit also supplies power to the horn, and when I close the switch, it just finds a path to ground instead of to the horn wire.

Whatever the case is, my “Debugging By Fire” approach damaged the slip ring contacts that allow you to have buttons on the steering wheel (Murdervan has the cruise control steering wheel buttons, but the actuator appears to have been taken out under the hood). I pushed a fix where I twisted a stripped end of wire very tightly around the spring plunger since the original wire attachment tabs had been melted off.

With the short now resolved, I tested that I in fact had dashboard and running lights again, and the horn worked. Again, I have no idea how these two problems were possibly inter-related, but here we are. This is what ghost hunting is all about, right?

Well, it’s certainly time to put this absolute disaster area together. But as I did so, I decided to go on an electrical binge and take care of an Annoying “Feels Good” thing that had remained unaddressed for a few weeks.

Up to this point, I had jumped the glow plug controller relay with a set of alligator clips hanging out of the doghouse/internal engine cover because I dug all of the fried electronics out of it before. So I’d jump in, connect the alligator clips, count to 10, and then disconnect them.

While I had the dashboard taken apart, I decided to make this hack permanent and run it to a button on the dashboard.

So to start, I wired one side of the contactor to the 12V feeder line coming from the battery. That means I just have to touch the other terminal to ground to throw the relay.

I ran this trigger wire up and around the engine cave, following other wiring harnesses, and into the dashboard area through some spare grommets.

I put this wire on the Magic Button that Murdervan came with. That’s right, it’s always had a Magic Button here. What did it do? Hell if I know, the wires ran somewhere underneath and just ended. I’m guessing it might have been a light switch or secret turbo boost/methanol injection button or something, since it was momentary and not latching. Whatever the case, it’s now the glow plug activation button.

The other side of the button was appended to the nearby main interior body ground.

And there we have it. I get in, push the button, count to 10, and let it go! This was the state I ended up selling Murdervan in – I never put in a new glow plug control module, and just explained it to the buyer who (as I mentioned, was familiar already with old Ford diesels) didn’t even bat an eye at it. I assume this is a common remedy for the dubious OEM electrical system anyway.