FLOSGLTRUCK

Hi everyone,

I am currently trying to install a Tekonsha Prodigy electric brake controller and am pulling my hair out trying to work out wiring routes !. Where did you guys and girls route the wires from the Tekonsha installed under the dash) back through to the GLs trailer plug ????.......under the carpet.............though the floor (after drilling a hole ????). Did you power the Tekonsha straight from the battery under the seat ?

Also - Looking at the SAM installed the plug seems fine, but when I did a temp hook-up in the back.....to ensure I didnt fart around fulling installing it to find out it didnt work - the Tekonsha unit shows up SH on its screen (which means trailer short). The trailer we know is fine because we had just used it with another vehicle also fitted with a Tekonsha Prodigy. Searching the next has suggested earthing the Prodigy DIRECTLY to the battery and not the car chassis (or I guess through the SAM green plug loom). Dod you need to use the SAM loom at all - ie cant you just wire it up seperately to the SAM unit (as you would with any other car.

An interesting thing I noted too was that the GL is too smart - testing the trailer plug on the GL I made a false indication of a blown right hand trailer turn signal globe - on the cars screen it tells you that your trailer has 'trailer right hand signal globe failure'...............smart *** car !!!

scottybdiving

Maybe I'm wrong, but I thought there was a plug-in in the wiring harness for a brake controller where you shouldn't have to run any wires, assuming you got the factory installed trailer hitch. I believe I read it here or in the ML forum.

neodoc

Maybe this will help.

FLOSGLTRUCK

Hi
yes you are right - there is a plug, but its at the SAM unit in the back - not under the dash ready to go.........real handy !

I am wondering where (read also as how) people are routing the wiring from the SAM plug forward to the Tekonsha unit and return to battery/or correct earths on the car body ?

FLOSGLTRUCK

thanks for the reply - I had received this prior to starting, but your posted version is much clearer. Unfortunately still doesnt get me what I need to know.

Has anyone here installed a trailer electric brake controller and are familiar with the wiring aspects of the install ?

boxerboy2

I need to know as well... Any help is appreciated.

BB2

scottybdiving

That's too bad. I just assumed that the wiring harness for the brake controller would be near where the brake controller goes .............just because Ford and Chevy trucks have had it there forever.

I can't help you with the routing, but it appears that the plug has both the power feed and ground for the brake controller.

tm4exc

Done a complete instal using an Odyssey controller. All post dec 2006 gls have the connector located just under the left side dash. There are 3 torx screws to remove. Be careful in the reinstall as the air delivery duct to the drivers footwell can easily come apart from the supply duct. The pdf to install the controller is listed above in post 3 by neodoc. It is current. You will need the connector and the little pieces to connect your controller pigtail to the connector as listed in the TB. PM me and I will call you an talk you through it if you like. This type of installation is only true if you have a factory installed hitch. Other wise your routing will have to run under the carpet through the wheel well.

FLOSGLTRUCK

Thanks Tm4exec,

I continued with the install myself (mine has the SAM plug in the back of the car - pre Dec 06).........frustrating !.

Started from scratch, only used the brake control signal from the SAM and pos directly to battery for the Prodigy.

In detail, as follows:

Tekonsha 'Prodigy' wire connections:

Blue - to trailer plug (to power trailer brakes)
Red - signal from SAM for brake application (this is connected to BOTH the black/red wire [0,75mm] and yellow/red wire [2.5mm] at the SAM)
White - negative (earth) to vehicle battery
Black - Positive to vehicle battery

Install took 8 hours, many a few choice words, but all is working as advertised. Hardest part, running the wiring neatly under the carpet and ensuring the routing will not potentially be cut on any sharp (unfinished) edges of the body under the carpet. In addition for safety sake any 'powered' or signal wire was installed with in-line fuses.

Next frustration, replacing three towbar bolts.............. the dumb *** who installed the factory tow bar actually bent three 8.8 bolts holding the bar in place - of course I didnt pick that up when the car was delivered new.............you shouldnt have to look at work like that done at a dealer to ensure they did it properly !

tm4exc

Well done! You will be amazed at what a great tow vehicle it is.

Danno4x4

Wow, sounds like you had a heck of a pain... You must have gotten one of the absolute first GL diesels produced... By december 06, they figured out that they had goofed and changed the wiring configuration...

Mine, like others, was right above the driver's feet, which, after I made the harness, made installing it very easy.

StevethePilot

You did the eel-lectronic brake controller? What are you towing with that beast?

FLOSGLTRUCK

a dual horse float.......float weighs 1800kg, plus each horse approx 550 - 600kg. Trailer has three axles (six electronic brakes brakes) !

Danno4x4

Not as frequently as I would like, but I am towing about 6800 lbs...

StevethePilot

I have seen this photo (or one very much like it) before. I've been trying to convince my wife if she rids herself of the Excursion and I use some of the proceeds to hook up the trailer hitch, there's no way we would exceed the towing capacity of the GL with that open trailer we currently use for dump runs. She seems to think we'll just scratch up and hurt the GL. Keeps forgetting it comes from the same country as the G-wagen and the Unimog.

STP

philip12

This belongs in the ML section, but the trailer experts seem to be here.
My ML had no trailer hitch, the dealer wanted to sell me that car, so they suggested that they would install the factory hitch, connector etc. to sell the car that they had in stock, I reluctantly agreed, and they did the install, when I first tried to plug a adaptor, 7 prong to flat 4 I had no lights on the trailer. I bought it back to them and they said they neglected to change the SAM, now they installed a different SAM, and re-programmed, I now only have a steady glowing prong inside the connector, (running lights) I can't find a lug with either left or right blinker, or brake lights. I put the headlights on, and switched the 4 way flashers on, no blinkers, do I need another adaptor 7 to 4 way flat, my trailer needs a left, right blinker, running lights, and a reverse gear lug, to activate the solenoid to be able to back up with disc brakes. Did they put the wrong sam, in, or re-program it wrong, or am I just missing something?

tm4exc

Assuming the dealer wired the SAM right, you need an adapter 7 to 4 way.
You can get them at any auto parts store. I carry one in the back of my GL just for rental trailers.
Just to make sure they wired it right, I have attached a pdf which lists RVI wiring standards. I got it from the delcity.com trailer site. E-trailer is also a great place to shop. The connector pins are numbered so you can check them with a multimeter and testing the left/right turn signal and running lights to insure your connector is wired right. Good luck!

philip12

Thank you for your reply, I have a 7 to 4 way, my question with what the dealer did is " at the connector plug, mounted on the hitch, I only have a steady powered lug, and no lugs that are blinking. I can only think either the sam is the wrong one, or they hooked it u[ wrong, the part they installed is?? 1 164-540-01-01,,,,, is there more then one SAM?

tm4exc

Hooked up wrong! Only pin 4 should have constant current when your engine is running. Pin 3 should be on when the vehicle running lights come on. The pin will not power when you have daylight running lights activated. Your 4 pin will connect to 1, 3, 5 and 6 if wired correctly by the dealer. Show them the diagram and get them to prove it to you.

Danno4x4

Phillip,

I would suggest that if the dealer did it, they need to keep working on it until they get it right...

Either going out and get a 7 pin tester that you can plug into the back of the vehicle or tow your trailer down to the dealership, and explaining the way that it should work, and the way that it is working now...

Tell them you would like it to work the way it should when you pick it up...

I have other friends that have had the same problem... Dealer charges them to wire the vehicle and it turns out the dealer did it wrong... They usually don't get it figured out until they get the vehicle loaded up for a trip and connect the camper trailer.... Frustrating.

Danno4x4

The photo is actually in another post here at MBWorld... I just borrowed it for this thread.

The GL is more than capable of towing a dump trailer... Do you currently have the towing package, or would you need to get it wired up. If you are keeping the Excursion only for dump runs and to haul a trailer every once in a while, get rid of it and save the insurance and FUEL costs.

StevethePilot

That is exactly my point in telling her we have to get rid of the Excursion. I'd have to have the tow package installed.

I wonder if anyone's made a custom trailer that follows the GL's lines? I've seen that done with some other makes like the PT Cruiser. That would look really slick, I think!

philip12

I took the car to a trailer shop today, they said there is only positive to (1) lug, it is correct there, there is no other power to any lug, no running lights, blinkers or stops, They have no idea why, and I didn't want them to touch anything other then tell me where the power is. The funny thing is, when the dealer installed the hitch, before they delivered the car to me, they never said that the SAM will have to be changed, now I bought it back, they changed the SAM, and I still have no lights, they keep talking about the SAM, I keep telling them I don't know about a SAM, and I don't care about one, the only thing I want is trailer lights, I can't even drive the trailer over to the dealer to show them that there is no lights, WHY,,,,?? because there is no Brake lights, running lights, or blinkers,, not very safe, or legal to tow the trailer over there. They said they changer the SAM and reprogramed the computer, but I still don't have lights..

philip12

I bought the ML back to the dealer, I left it there and they called to say it was working now, they had to flash the computer?? I have current at all of the correct lugs in the 7 prong connector, but when i USE A TEST LIGHT TO CHECK THEM, i GET A WARNING ON THE DASH THAT RIGHT/LEFT blinker on the trailer is blownOUT?? Why did the computer have to be flashed, they did this the week before,

Danno4x4

Not sure why they would have to re-flash the computer... Other than to say Germans car makers notoriously over engineer the simplest things...

Regarding the trailer light out warning, the computer is probably programmed to look for a certain level of current draw from the trailer turn signals, and most likely its the draw from the average incandescent bulb. Since the tester likely uses LED lights, they don't draw nearly as much current as the incandescent bulbs which triggers the warning...