'84 Excella dash rewire, spare wires

[WayneG]

Winter is here, and it is time for some long overdue upgrades for the 84 Excella 270.
It all started with wanting to upgrade the radio to something modern, but that needed the dash pulled in order to cut a din slot. Taking the Dash out lead to writing down all the wire connection locations, and that lead to wires without homes.

Eventually I will writeup my dash rewire with LED's and the Radio/DVD/GPS/Rear view camera setup, but for now, I have a puzzle that needs to be solved.

As I am identifying wiring, I found 4 wires (2 red & 2 black) starting nowhere and going through the firewall.

One pair looks to be for the now defunct electric radiator fans relay and thermostat as you can see in the upper left of the photo.

The other pair goes to this coiled resistor or shunt? in the right side of the photo, There is also a yellow wire zip tied to the bundle going toward the engine.
The red wire runs through a circuit breaker on the firewall (as shown in the second photo) and was just dangling behind the dash cut off and stripped with no obvious origin.
(I would have traced it further, but the temps are less than 10 degrees and we just got a foot of snow)

Thanks in advance for your help.

PS: Anyone else out there look behind the dash and find many of the wires with inline splices in them, as shown in the third photo?

[gunner]

The coiled resistor or shunt as you called is normally incorporated with tag axle motorhomes. Since the tag axle is similar to a trailer brake assembly with magnets the resistor controls the voltage going to the brakes. Sliding the adjustable slider that goes across both coils upward increases the voltage sliding it downward decreases the voltage. Since you don't have a tag axle it could be used to control the electric brakes if you tow a trailer and have an old style brake controller.

[tony6373]

Hi Wayne,

The resistor sure looks like the adjuster for the old style trailer (or towed) brake actuator. These nearly 30 year old M/Hs have usually seem some modifications in there lifetime. I have found some patch work behind my dash also. I'm planning a radio upgrade, tire pressor monitor and rear view camera so please keep us informed of your progress.

Just got my 270 back from the Rush Truck Center where it had it's fluids changed. The Allison transmission seems to shift much more aggressively!

[WayneG]

Originally Posted by tony6373

Hi Wayne,

The resistor sure looks like the adjuster for the old style trailer (or towed) brake actuator. These nearly 30 year old M/Hs have usually seem some modifications in there lifetime. I have found some patch work behind my dash also. I'm planning a radio upgrade, tire pressor monitor and rear view camera so please keep us informed of your progress.

Just got my 270 back from the Rush Truck Center where it had it's fluids changed. The Allison transmission seems to shift much more aggressively!

I would never have figured that out, I had been ignoring the manual pages for tag axle info.
It is in there on page 29. I would guess by the way the wires were just dangling under the dash, at one time it had a brake controller.
One thing that threw me off was that the ground for the CB radio went to the bottom screw of that resistor, which I am guessing is ground. I don.t know why they did not wire it to a ground under the dash. The +12 for the CB was crudely spliced into the power wire off of the wiper switch.
Thanks for helping me with that!

With the temps back above freezing I was able to do some more wiring behind the dash. I have finished the dash, I just need to fix up the rats nest of wires behind it. Since I have access to surplus gear, I am installing connectors to make future dash removal easier.
I will do a proper writeup of my work when it is complete.
For a quick update, from left to right:
1) Since I installed LED's to replace the dash bulbs, I installed a separate dimmer control between the light & wiper switch.
2) The old speedometer worked but the glass was dirty inside making it hard to see. I did manage to open it and clean it, and I would have installed it but I found a new one with trip odometer cheap enough to go for it.
3) I use to have the TPMS power wire going to the left lighter outlet. I drilled a small hole in the dash and I am powering it off of the ignition power now.
4) All of the indicator lights have also been converted to LED and the Aux heater switch has been converted to the power switch for my cameras. Rear view and Right mirror view.
5) The heater/AC control was broken up, I found a replacement online that fit perfect.
6) I added a indoor outdoor Thermometer/Clock to replace the old LED clock. It also has battery voltage, that I hooked to the Coach battery to monitor it.
7) I cut a single height din slot where the original radio was. I bought a Pyle PLBT72G, it is a inexpensive unit for what it does. It has a pop out video screen with built in GPS and Rear view camera display. I angled it slightly to hopefully give a better viewing angle from the drivers seat. (In the picture, the faceplate has not been installed yet.

All of it untested, so I hope it works out.

[tony6373]

Looks good. I like the connectors idea. Where did you find LED replacement lamps that fit the gauges? And a dimmer that works with LEDS? You are inspiring me to do some serious rewiring behind the dash. I need to replace the EGT gauge and lub the speedo cable at the very least.

My M/H is diesel and has no manifold vacuum so there is a vacuum pump on the back of the alternator (I think) but it does not make enough vacuum to operate the hvac blend doors. Maybe I have a leak someplace? The cruse control does not work either but I'm thinking it would be best to just get a new all electronic replacement.

I have been thinking about removing the glove box door. That would give me a place to mount a CB and the 2 meter radio.

[WayneG]

It took a bit of engineering to get the LED conversion done, it could be a difficult task, if you dont have access to the right parts.
I could not find a commercial product to do the entire job, so I MacGyvered my own solution.
I looked for some LED's with a good light output and wide angle dispersion to minimize bright spots. For the indicators I used a single LED and a resistor to keep the current to 20 Ma at 14 volts. I did not get a photo of the indicator light bank, but the first (out of focus) image is the resistor & LED I used. I found some surplus rectangular 500 ohm 1/2 watt resistors that fit inside where the bulb was and I soldered the assembly inside each bulb well.
For the dash lights I used 2 LED's and a 400 ohm resistor as shown in the 2nd photo. I had to drill holes in the lamp base to thread through the leads and solder them on the back. The black walls was also reducing the light output so I added a 1/4" strip aluminized mylar foil to walls to help with that. I have not tested this in the vehicle yet but on the work bench it looked as bright as the original bulbs.
For the gauges, I used standard LED T10 bulbs from Amazon (Jtech 10x 194 168 2825 T10 5-SMD White LED Car Lights Bulb) They were cheap, we will have to see how they last.
Since the stock dash light dimmer was made for standard high current bulbs, it would not work with the LED's so I needed to dim the dash lights with a Pulse Width Modulated dimmer. Since the PWM dimmer runs the +12 through and modulates the negative connection, it would not work with the common ground of the dash lights. I had to modify the gauges and isolate the bulb negative from the gauge ground. In my previous photo, you can see some ceramic standoffs on the ground posts on the back of the gauges. I had to cut the copper run between the lamp and the post and run a wire to the top of the post for the PWM dimmer to control.

On the cruise control issue, mine did not work when I got the 270. I bought a NOS controller and that did not work either, so I bought a Rostra Universal, and it works great. Since they were interchangeable, I even kept the original turn signal control switch. I dont know how well that will interface with a diesel engine, but since it is all electric, at least it wont require a vacuum connection.

[tony6373]

Merry Christmas Wayne,

Thanks for the LED and cruise control information. I wish I had access to a good big electronics parts source but the nearest Fry's is about 60 miles away. The local Radio Shack has very little. And I sold all my small parts when I decided to full-time back in '01.

Is your M/H really yellow? I'm thinking of having mine painted silver with a big red stripe around the belt line. Talked to P&S and decided not to re-clear coat.

[WayneG]

That photo is my first, it was a 20' 1977 Argosy that I painted like the Yellow Submarine.

I sold that several years ago then bought another 77 Argosy, 24' for more room. That was just sold in October to someone from Germany who had it shipped overseas. Unless something extra special crosses my path, the 270 will be a keeper.
It needs some body work, the previous owner was not the best at parking and there are some minor, but ugly dents that need to be worked on, so I have not put its photo up yet.