Another, what were they thinking? thread


#1

Just ran into this over the holidays- my Trailblazer has embedded XM receiver and it just failed with a No Signal message on the display. I did a bit of searching on the internet and found the usual half-correct information but enough for me to locate the receiver, wiring connections etc after a bit of disassembly.

Fortunately, I have a car kit in another vehicle and so I could substitute the antenna from that. It plugged directly into the receiver and viola! works again.

So now I need to determine if it is the vehicle antenna or cabling from receiver to antenna. The antenna is above the headliner on the passenger side. Removing the visor and heysoos (sic) handle, I can access the antenna and connection to the cable. The cable runs down the passenger A pillar, across the dash vents and disappears into the frame only to reappear behind the lower hush panel by the receiver. It would not be easy to replace. One documentation source shows another connector hidden along the length but almost impossible to verify on the vehicle.

Here’s where it gets maddening. The radio has a male connector. So does the vehicle antenna. So the cable connecting them is female to female. This means I cannot plug the antenna directly into the radio! Nor can I plug my replacement antenna into the cable! I can’t check anything without buying some replacement parts first. What bonehead came up with this scheme?!? Why would you not have the entire chain M-F-M-F? As it is, nothing can be substituted to isolate the problem…morons.

Don’t get me started on the XM antennas either. The car antenna connector is ever so slightly different than the home antenna connector. Just enough so they cannot be interchanged. The OD of the barrel is just a hair too large. The center pin is recessed into the insulator a micron more and they cannot be swapped. There is no other reason they could not be swapped, the antenna itself is the same construction…


#2

Wouldnt be the first time things were made a little out of spec ,so as to not be interchanegable,during WW2 guns were made so the enemy couldnt use thier ammunition(nato rounds are interchangeable) and the list goes on,I wish car manus still used sealed beam headlights.


#3

Not sure which connection you are talking about, but it sounds like a gender bender (perhaps a local slang term might work),


#4

Oh, I’ll fabricate a patch cable but I have to order the parts. I don’t have SMB coax on hand. System uses Micro coax like rg405 or something. Point is, it shouldn’t need patch cables to debug!

I hear you kmccune. But this the same manfr making both antennas for their already proprietary radio. Not like I’m going to unbolt my home antenna from the house and fish 50’ of cable every day so I can swap it between home and car to save $30 on a second antenna…hard to understand the motivation, assuming it was intentional :stuck_out_tongue_winking_eye:


#5

Sometime one gender of connector is less likely to be damaged than the other by being banged around when the gadgets are in piles at the manufacturer awaiting shipments. Cables are less likely to get damaged when being banged around by other cables b/c they don’t weigh much.


#6

The manufacturer spent a lot of money designing a feature that is so difficult to repair that you should want to go to the dealer to fix it. Resistance is futile, Earthling.


#7

Cables are less likely to get damaged when being banged around by other cables b/c they don’t weigh much.

Then that would be an argument for them having the male end rather than the more robustly enclosed female end, right?

Actually, neither end is likely to be damaged due to handling. Like most micro coax connectors, both genders have an outer shield protecting the gender based connection in the center. The outer shield extends well past the inner cones, protecting them from any “banging” around they might encounter during abusive handling.

Resistance is futile, Earthling
:smiley:
The force is strong in this one…


#8

@TwinTurbo writes …

Then that would be an argument for them having the male end rather than the more robustly enclosed female end, right?

I don’t know what the difference in appearance is between the male and female version of the connector. If the connector in question was an F connector like the one in Barky’s photo above, they’d put that gender on the radio & antenna since everything is flush and nothing sticks out, and the cable would have the gender where the wire inside poked out. If they did it the opposite way, that is indeed strange.


#9

I suspect that there is no detail too small for a designer/engineer to have made a decision for some reason regarding it. Who knows what it was but there must have been a decision made on it.


#10

George, this is not exact but a close diagram of the connector configuration. The working parts for both ends are recessed…


#11

I think most manufacturers would put the “plug” side on the stereo and antenna, and the “jack” side on both ends the cable.


#12

Why?
As it is, imagine you have NO cable, just the antenna and radio. The radio would have the plug and the antenna the jack. The cable should just be an extension between the two. When the M-F cable is connected to the radio, the far end is still a plug. And now you can eliminate the cable for diagnostic purposes and just plug right into the radio. I do not see the logic in your proposal- enlighten me…


#13

I can see your point that it would make it easier to test, as no cable would be needed. But the reason the manufacturers do it that way I’d guess is because that pin that sticks out in the jack could possibly get bent or broken off. There might put 500 finished units in big bin awaiting boxing, etc. They’d be concerned about them getting jostled around during the manufacturing and shipping process and that pin gets bent. There’s nothing corresponding to that pin which sticks out in the plug.

And I expect it is partly just by convention. It’s the same with my tv and antenna connectors. Both my indoor tv antenna and the tv are equipped w/ the plug version of the F connector. The connector face is flush, nothing sticks out. The cable between them has the jack on both ends, with a pin that sticks out similar to your “jack” diagram above. So there’s no way to connect the antenna directly to the tv except by using a cable or adapter.


#14

To answer the earlier question, a “male” connector has the insulator recessed and the center conductor sticking out. A “female” has the insulation out to the edge of the outer housing and a metallic-tube lining in the center hole, for the “male’s” center conductor to slide into.

There are adapters to connect two “male” ends together and adapters to connect two “female” ends. They’re dirt cheap, and available anyplace that sells coax. Radio shack, electronics stores, maybe even Sears.


#15

Ten years ago I had extra cables and satellite radio antennas in my tool box to assist in diagnosing these problems. It seems that there was a rush to market of these systems from 2004-2006. The service manual had no diagnostic information and we had no training for these systems (satellite radio, hands free phone, park assist, etc).

In most cases the antenna failed. The cable can be damaged but can be checked for continuity. There was also a number of customers who complained of satellite radio failure, after calling Sirius I learned that their subscription expired.

I got out a Mopar kit, the the antenna has a female connector, the radio a male.


#16

George & TSM, maybe you should look more closely at the diagram I posted. I also described it a few times. The male pin is recessed well back of the outer shield. It is nearly impossible to damage it by tossing it around in a bin or any other inadvertent abuse.

And TSM, good luck finding a coax bullet for RG405 at rat shack or any other place that sells “coax”. They have those for RG45 or RG6 but this is miniature coax. Completely different animal.

Nevada- you nailed it. This is a 2005 vintage Trailblazer. Seems strange to me that a passive antenna would fail but rest assured, I will be disassembling it to find the root cause. In my circumstances, it would seem more likely to have a mouse chew through the cable as it’s parked outside and mice are a constant battle. I can perform a continuity check on the cable. Heck, I could do a full spectrum sweep but the main point was one of over-complicating the thing in the first place when they “designed it”.


#17

I think it is just a simple case of “you need parts? You have to get them from us”