Trailer hitch

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storm9c1
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Location: Pittsburgh, PA

Re: Trailer hitch

Post by storm9c1 »

OK, sorry for the delay on this folks. CP was crazy fast with shipping. I was amazed to have the towbar in 3 days! But then life intervenes, and next thing you know, you have a 2011 Caprice, minus a bumper sitting in your garage for a month... (keep in mind that I took the bumper off over a month ago to see what impact beam was installed for CP and never put it back on, lol)

So I finally got the G8 towbar installed. And the news is good! It fits perfectly.

Mechanical caveats:
Installation is easy. The only thing that needs to be removed is the bumper cover/fascia and stock bumper mounts. Then this towbar slides into place. For 2011 cars, the fascia has the pattern/cutout, and a sharp utility knife made short work of that as instructed. That's it!

The impact beam needs the holes to be elongated about 1/4" to bolt up (which CP warned me about). This is a super easy mod with a dremel since the impact beam is aluminum. Otherwise it fits perfectly! Pictures of this detail will come later. CP also has good pictures of this.

CP sent 2 long bolts since the Holden kit only comes with 2 -- and 4 are needed. However, after researching this, the diagram shows that the G8 has 2 short bolts and 2 long bolts. You are supposed to reuse the 2 long bolts on the car and replace the 2 short bolts with the 2 new long bolts in the kit. Well the Caprice already has 4 long bolts installed by default. So if you reuse those, you need NONE of the bolts that come in the kit. Or since CP is awesome, you can use the 2 new bolts he includes along with the 2 new ones in the kit, and have 4 new bolts all around FTW. Which is what I did.

There are 2 "ball" thread sizes that is available here in the USA (for a standard 2" ball). 3/4" for class 2 and smaller. And 1" for class 3 and larger. Problem is, the receiver from AU has some in-between metric size. So I had to purchase a 3/4" ball and use a very heavy washer. Or the other option is to drill out the hole to 1" for a class 3. I'll never be towing class 3 loads, so I am fine with class 2. For now.

I temporarily fitted the bumper fascia -- and the receiver sticks out enough to insert the pin! Cool cool cool. I know this was a problem on the G8. But not on the Caprice.

Then I removed the fascia again to install the wiring.

Wiring caveats:
The wiring is the next nightmare since the stock Holden harness comes with a converter box to divide the signals.

Overview: The stock tail lights on a Caprice have integrated brake and turn signals. But the box that comes in the kit separates them for a 7-pin harness setup. My trailers only have a 4-pin setup (combined signals), so I actually do not need this. If I used the Holden harness and then bought an adapter, then the signals will be as follows: BCM -> combined brake+turn -> harness -> box -> separated brake+turn -> converter -> combined brake+turn -> trailer. This is ridiculous.

So what I am going to do is mount the Holden converter box, but leave it unplugged in case I need a 7-pin harness later. Then I'm going to make my own converter box with 3 relays to keep the signals combined but use power from the 30A fused circuit intended by the kit. Yes, I could piggy back directly from the brake light circuits and make my own harness driven directly by the brake lights from the BCM. I assume this is what others may do. It's the lowest hanging fruit. But the Holden engineers made a separate fuse/circuit for trailer power for a reason to isolate the trailer from the car (I suspect so a fault doesn't damage the BCM or blow any of the car fuses). Power comes from the unused F7 cavity in the trunk fuse block. So I'm going to retain this engineering isolation.

I'll have pictures once the project is complete.

CP, I may want you to see if you can get the male side of the plug for the converter box separately. That may be difficult since it's integrated into the block box. But it's worth a shot. Then the harness I make will be completely plug and play.
Last edited by storm9c1 on Mon Aug 19, 2013 7:48 pm, edited 1 time in total.
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.
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Crazy Paul
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Re: Trailer hitch

Post by Crazy Paul »

storm9c1 wrote:So I finally got the G8 towbar installed. And the news is good! It fits perfectly.
This is excellent news to us all. Thanks for being the pioneer on this and for taking the big gamble on possible fitment issues.
storm9c1 wrote: CP, I may want you to see if you can get the male side of the plug for the converter box separately. That may be difficult since it's integrated into the block box. But it's worth a shot. Then the harness I make will be completely plug and play.
I didn't open the bag of harness parts and take any detailed pictures. If you can get me a clear picture of the connector which is integrated, so I can see the outline shape and number of cavities, then I should be able to come up with a matching male connector and terminals for you.
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storm9c1
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Location: Pittsburgh, PA

Re: Trailer hitch

Post by storm9c1 »

Crazy Paul wrote:
storm9c1 wrote:So I finally got the G8 towbar installed. And the news is good! It fits perfectly.
This is excellent news to us all. Thanks for being the pioneer on this and for taking the big gamble on possible fitment issues.
Somebody had to try it. :) I'm thrilled that it works.
Crazy Paul wrote:I didn't open the bag of harness parts and take any detailed pictures. If you can get me a clear picture of the connector which is integrated, so I can see the outline shape and number of cavities, then I should be able to come up with a matching male connector and terminals for you.
Forget this. I ran into another problem tonight while trying to mock up the wiring. The PPV is missing an entire circuit. I believe it's the power from fuse F7. Using a flashlight, I was able to inspect the fuse holder and it is missing the cavity. Upon further inspection, the wire colors are different in the plug-and-play harness, so I don't even want to guess which wire(s) are missing and which need to be manually connected somehow. Long story short, it just doesn't work and I don't want to spend any time trying to fix it since it isn't going to do what I want even if it did work. Essentially this means that we can never run a 7-pin trailer plug unless more work is done to make the little black box work properly.

But I am fairly confident that I can wire up the 4-pin harness using the relays (as I described above). Knowing the little black box isn't going to work, I am just going to gut the box, de-solder the male connector from the circuit board and mount the relays inside there. This essentially creates my own version of the little black box for a 4-pin harness. As I said before, this is the hard way. The easy way would be to skip the Holden trailer harness altogether and tap into the tail-light harness directly and let the BCM circuits drive the trailer lights. But I like the idea of the trailer being electrically isolated through the relays. And I like the idea of hacking up the add-on harness rather than the stock vehicle harness just to keep the car as original as possible and this modification as plug-and-play as possible.

I'll keep you all posted.
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.
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Crazy Paul
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Re: Trailer hitch

Post by Crazy Paul »

Great thinking to make use of the enclosure and structure of the supplied 7 pin harness to construct a stand-alone 4 pin arrangement. I'm glad the WM wiring schematics for trailer connection that I found were useful to you.
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storm9c1
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Location: Pittsburgh, PA

Re: Trailer hitch

Post by storm9c1 »

Teaser pics... Fascia is still not installed yet. Been working on the wiring.

Here is the little black box. Original guts on the right. Useless to me. New guts on the left that I built with 3 relays. Not the most pretty thing, but who is going to see it inside the black case? I reused the plug that goes into the trailer harness. And at this point, I only had to cut two wires on the trailer harness and zero wires have been cut on the car itself. Power to the harness is being supplied by the battery junction on the passenger side next to the aux battery area in the trunk. All plug and play.
Image

And here is the towbar installed prior to adding the impact beam. That class 3 receiver looks monstrous, doesn't it?
Image

Other technical notes:
There is no switched ignition signal in the trunk that I could find and missing the complete schematics from my Helm manual didn't help. So coming off the aux junction box (which is hot all the time), I added a 15A fuse for the harness power and manual power on/off switch for everything -- so the relays and trailer harness are only active when I turn the switch on. This is also handy for launching a boat, when you normally need to disconnect the lights to prevent the light bulbs from shattering when they come in contact with water. So the switch serves two purposes (a safety disconnect when not trailering, and a convenient disconnect when launching a boat).
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.
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elc32955
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Re: Trailer hitch

Post by elc32955 »

Not bad! Tom, since you were the guinea pig on this one you're in charge of the write-up for the tech section for those that will follow down the road :)

Another issue put to bed! CP, as always thanks for your help & support of our community. Good job everyone!

Thanks
Eric
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
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storm9c1
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Location: Pittsburgh, PA

Re: Trailer hitch

Post by storm9c1 »

More pics. First one is of the towbar with the impact beam reinstalled. Instead of drilling a hole in the trunk floor as was recommended in the instructions, I was able to route the tow harness out through the rubber plug (on the right) just above the impact beam.

Image

Note in the picture below that the escutcheon around the hole cut in the bumper -- it works. The pin fits fine, even with the escutcheon on these cars (unlike a G8 which apparently is a problem).

Image

The escutcheon didn't fit perfectly though. The top fits tight against the receiver. Kinda needs warped to snap into place. Could have been caused by tolerances from cutting, not sure. I wasn't going to trim it more because there isn't much you can cut before it will be too loose. Not sure the escutcheon (at $50 a pop) is worth it.

I should see if I can get the lower fascia piece (that I had to cut) to keep in stock in case I want to return the car to original condition.
Tom (AKA: Storm)
2011 Caprice 9C3: L77, 8K miles, first-owner, purchased July 2011.
1995 Caprice 9C1: LT1, 178K miles, summer car.
1995 Impala SS: LT1, 21K miles.
1995 Caprice Wagon: LT1, 62K miles.
1995 Caprice Wagon: LT1, 128K miles. Rust In Pieces
1994 Caprice 9C1: LT1, beater winter car.
1969 Chevy C30: 383ci stroker, 4L80E, rollback car hauler.
1972 Chrysler Newport: 400ci big block, survivor 27K miles, 2-door hardtop.
1969 Dodge Charger: 383ci big block.
Navy Lifer
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Re: Trailer hitch

Post by Navy Lifer »

Well, I can tell you that there at least 2 of those panels not in use, so you might give Scott (novadeuce) or Steve (Eckart) a shout to see if they would offer theirs up for cheap. It's not an inexpensive part, I recall.

We're still waiting for Steve Eckart to provide pix of his G8 hitch install for comparison, but I don't think he will have detailed commentary for his, as he isn't using it to tow.
Pursuit
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Re: Trailer hitch

Post by Pursuit »

Just noticed that in the 2011 Michigan Police Vehicle Evaluation test, page 10, the rear view of the Caprice shows a trailer hitch. Hey, It's 3:40 am I have some free time....
Maurice Sheil

mhsheil@gmail.com

2011 Caprice Phantom Black 9C3
2012 Impala 9C1
1995 9C1 Caprice
1996 GMC Sierra C1500
1996 Chevrolet K2500 Extended Cab, long box, 454, 91,000 rust free miles
1974 SJ Grand Prix 455 well optioned with factory moon roof
ImpalaPPV
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Re: Trailer hitch

Post by ImpalaPPV »

The Caprices in the 2014 MSP tests have hitches installed...as do the ones I have seen on patrol here in Arizona. I know this post is a year late.
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