so i get back from a 3 week trip and can't wait to drive my xjr again...so i am driving about 10 mins into my first drive after 3 weeks...and i am talking to mom via the motorola t605 and my iphone, and then i hit a bump and the volume drops to just about nothing...it is back to the same problem i had where the phone volume would drop to just about nothing intermittingly...the thing is, i replaced my head unit and my amp and now the problem is back, out of the blue...after i replaced the head unit and the amp everything was fine for weeks, and then i go away, come back and now i have the same damm problem...so today after it happened, i pulled over, turned the car off and back one, and bamm, everything is fine again...sure enough though the problem happened again about 20 mins later..i just can't take it anymore...i need to be able to talk on the phone in my car...any ideas what would keep causing this, after i replaced the head unit and the amp? what else could it possibley be? what else should i replace?...pls help

 

@pdog

Sorry mate, that sounds like a nightmare. I have the T605 in my XJR with the premium sound and its brilliant.

Here goes nothing....

I am assuming this sudden drop in volume only happens when you are on the phone (and not listening to the radio or CD or tape, etc) ?
Question...... do you run music through the T605 as well (either via bluetooth or via the aux in) ? If so, does the music volume ever drop off ?

If you have already replaced the HU and the Amp, would it make sense to replace the T605 next ??

Does it only do it when the car is moving ? or does it do it after a certain period of time ? (Sounded like it worked for 10-20 mins, then failed, then after you stopped and restarted it did it again after 20 mins) I'm wondering if there is a loose wire somewhere, or something loose on the board inside the T605 that is moving around and causing the problem.... if so you would only expect the issue to happen when the car is moving..... If it happens after time even when the car is stationary, could it be something is heating up? or charging up ? (and turning the car off and on again gives it a chance to recover itself for a while?)

 

You hit a bump and the sound level dropped off... I'd look first at the connection between the T605's cable and the Jag's connector (inside the console) for a loose connection on the two phone audio signals. Second, at the T605 connector for the same two signals. If either is loose, dirty or corroded, a bump could make it high resistance. Sitting for a while or powering down and up again can cause an intermittent connection to work again.

 

hey guys - thanks so much for the tips...i use to have this problem before i had the T605...when i first started having the problem i replaced the factory phone first and then put in the T605 but still had the problem...i guess the connections could be the issue...i was thinking about running all new wire today to eliminate the connections...i am determine to fix it or do something else... do you think it could be the CD unit or Nav unit? do you think that is possible?

 

@pdog

CD Unit --> well, I am assuming your phone sound goes from the T605 into the factory phone harness in the centre cubby ? If so, I can't see how the CD player could be part of the problem.

Nav unit --> Again, this shouldn't be interfering with the sound, but this premium system is weird to put it mildly. It may be worthwhile just for process of elimination to disconnect the Nav to confirm that the phone sound does still work if the Nav is disconnected.

I think another test you could do would be to temporarily fit the speaker that comes with the T605 and see if that gives you constant volume on your calls. I'm 90% sure it will because now that you've mentioned you had this problem even with the original factory phone, it sounds like the fault is with the car and not the T605.

I like quads idea about a loose connection being broken by a bump..... I was asking some other questions back to you about whether it happens only when the car is moving, kind of thinking the same thing.

@Quad

If the symptom is ok sound goes suddenly to low sound (and not no sound or crackly sound) can you think what wire could be causing this ??? Would this happen if you lost the ground ? I am assuming if you loose the signal wire connection you would get no sound and or crackly sound, but if you lost the ground would you still get something getting through ?

If you think pdog is losing a ground then maybe he could add an extra one somewhere and then retry ?

 

It depends on whether the head unit's input is single ended or differential coupled. If single ended, losing the input ground (phone audio - ) would likely just add significant noise to the input, but with a differential input, losing either the phone audio + or - will effectively break the circuit and all signal is lost.

 

hey guys - thanks so much...here is more info...the volume doesn't go away completely it is just way reduced when the problem happens...so the volume is normally at 10 for me to use the phone, when the problem occurs, i can turn up the volume to 35 and barely hear the person on the other end of the phone but i can hear them barely...i am now thinking i need to check the mic to see if my voice would be audible to people at the same level when the problem doesn't happen as that might be some useful info...also the issue happened to me last night before i even moved the car...i started the car and the dead giveaway is those beeps that the T605 does when the car starts and the blue tooth connects to my phone, it gives those two beeps, those are way low and i know the problem has occurred...so sometimes it does happen upon starting the car and others while the car is moving...so now i am thinking of taking out all the wirirng and running a new harness...and changing the connectors...there is another factor that might be playing into this in that my mechanic fixed by cigarette lighters which weren't working and now i am thinking he must have done something to the wiring or tugged on the cables too hard...what do you guys think...

happy holidays...

 

@pdog

Defenitely sounds like a loose wire somewhere. And In my experience, almost 80% of "car problems" are actually as a result of a human being involved and doing something they shouldn't have done. I'd ask the mechanic exactly what he had to do to fix your lighters, ie which parts of the car was he working on, centre cubby, fuse boxes, etc, then go in there yourself and see if you can see something.

 

Hey i just tested the mic and it works fine when i am having the issue...meaning when the cellphone volumes drops low the mic input level stays the same and is not at all affected ...will be focusing heavily on the wires now.,..will let you know how it goes...thanks again all

 

Both lighter's wiring is in the general vicinity of the phone connector that the T605 is connected to - I'd be pulling the console storage bin (4 screws) and looking at that connector for loose wiring.

 

thanks, i also noticed that the internet connect for some of the phone's to radio head unit cabling is in the LH healboard...i am guessing this could be where the problem is...will be checking that as well...

 

I follow the mantra - cause and effect - if something was done, and a problem occurs shortly thereafter, there is usually a relationship. Your mechanic was working on wiring right next to the connection between the T605 and the Jag's phone connector... If you don't look here first, you likely will be looking there last!

 

finally after many many hours spent i think i found it...it was a crimped wire, or a dirty terminal on the following connector...that plugs into the back of the radio head unit...the yellow connector with the locking lever

 

@pdog

Great ! Lets hope thats fixed it

 

oh well i guess i didn't fix it afterall...i hit a speedbump today and the issued happened again...now if i hit the radio lightly the problem goes away, so it is definitely the connector into the headunit for sure...i am trying to figure out the best way to handle the crimped wire that keeps acting up...it is to close to the connector to use a butt splice, so what would be the best way to handle it...if i got a new
IC11 / 26-WAY AMP MICRO QUAD LOCK / YELLOW connector would it be easy or hard to connect all the wires to the new connector, i could then take out the crimped wire all together...