strange issue, radio only works when fan blower is set to4

spreyjay

New member
.well this has me stumped, I can only use my stock oe radio with the fan blower set to its highest speed. Dropping it to any other speed makes the radio cut out. It does not need the code re adding when I go back up to full speed on the blower, it just Suddenly comes to life.

Blower itself works fine on all settings.

Any ideas?
 

Aqua Puttana

Poly - Thread Finder
.well this has me stumped, I can only use my stock oe radio with the fan blower set to its highest speed. Dropping it to any other speed makes the radio cut out. It does not need the code re adding when I go back up to full speed on the blower, it just Suddenly comes to life.

Blower itself works fine on all settings.

Any ideas?
Could be some sort of backfeed loop. I would first check all of the fuses under the steering column. Don't just trust the fuse map because that information can be incomplete.

If all of those fuses are ok, then check the fuses under the the driver seat. Fuses there are less likely to be the culprit, but you never know with Mercedes.

Use a flashlight. An open link can sometimes be difficult to see.

vic
 

autostaretx

Erratic Member
On fuse block 1 (under the steering wheel), check out both Fuse 8 and Fuse 15.
Fuse 8 is the "permanent" power to the radio, Fuse 15 is the "key turned on" power.

((i'm still looking at the schematics for a blower/radio cross-feed))(4 splices (S250, S252, S255, S210) are my prime suspects)

(a few moments passed...) Does your cigar lighter socket follow the same pattern?
(not the 12v power outlet on the panel, but the socket that's hidden in the front ashtray)
That socket also is tied to splice S252 (hence fuse 8).
.. but since your radio is not losing its Code, i doubt that that circuit is the one at fault.

Chunks of the Aux Heater system do share the same Ground point (G203) as the radio.

I suppose i could always cop out and suggest that it's damage inside Fuse Block 1 that's causing cross-connects.

--dick
 
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TJD

New member
Hi- my 04 does the same thing. It used to not work until I touched the brakes, then that quit working. Then I discovered that if I hit both window switches together while they were already up and held them momentarily the radio would come on. That no longer works and has evolved to the blower on high scenario. Help!!!
 

BrennWagon

He’s just this guy, you know?
The first thing I’d do is replace the fuses for the radio and fan circuits. The fuses themselves may have corrosion on or in them, next Id check the ground for the radio and blower motor. When adding an amp I initially tried using the radio ground with poor results. I think that’s because the ground wire is only rated to pull stock power as it’s a relatively light gauge. I used a self drilling self tapping screw to create a new ground point in the metal framing of the dash. If nothing else, you may luck out with that approach.
 

ECU

Well-known member
What has been modified in the truck?
I hooked up my backup cam to the reverse light and found that it affected shutting off the truck. I needed to check my wiring.
 

TJD

New member
I forgot to mention that I just replaced the fuse panel entirely-no help. Between this issue and the lock-unlock-lock gremlin it’s amusingly aggravating.
 

Aqua Puttana

Poly - Thread Finder
Ground issues are worth exploring.

I forgot to mention that I just replaced the fuse panel entirely-no help. ...
Did you double check for any blown fuses after the install? A long shot, but that should be eliminated as a possibility.

Assuming that it eventually got resolved, it's too bad that the OP didn't get back with whatever they found.

:2cents: vic
 

TJD

New member
I checked all the fuses, pulled the unit out and looked around. Nothing obviously amiss, I surrendered and ordered a new head unit. What are the chances that the new unit will inherit the same behavior?
 

Axiom

Mike from Florida Van Man
Pretty high unless you got a different brand radio and plan on wiring an adapter to the end of the stock harness. Did you check the ground strap by the fuel filter? What about where the battery is grounded on the firewall? If you're putting a different type of radio in (i HIGHLY recommend it, screw the factory radios) look closely at the wires you hook up. Don't hook up any KLINE wires, I believe it was a blue one on my Sprinter.
 

Aqua Puttana

Poly - Thread Finder
... If you're putting a different type of radio in (i HIGHLY recommend it, screw the factory radios) look closely at the wires you hook up. Don't hook up any K-LINE wires, I believe it was a blue one on my Sprinter.
:thumbup:

Additionally. Be careful if buying an aftermarket adapter connector be certain to verify that the pins go where needed. Some have crossed pins.

Personally I just chop the wires and splice. The radio has a connector if future removal of the head unit is needed for some reason.

Some wire color info is here.

https://sprinter-source.com/forum/showthread.php?p=40679#post40679

:cheers: vic
 

TJD

New member
I’ll check the ground by the fuel filter-got a cheap kenwood coming. What is a KLINE? Thanks
 

Aqua Puttana

Poly - Thread Finder
... What is a KLINE? Thanks
K-line is the communication method used by OBDII scan tools to access the T1N Sprinter modules. (Newer Sprinters use CAN bus.) There is at least a speed sense wire to the OEM radio which, if improperly connected to an aftermarket radio, can affect the Sprinter module communication.

Don't connect any wires to your new head unit unless you're 100% certain that they are correct and necessary.

I've had good success using a lower end Kenwood unit... until my K9 co-driver snapped a USB stick off. Everything still worked, except the USB music which is my go to. :bash:

:cheers: vic
 
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Aqua Puttana

Poly - Thread Finder
I installed an $89 kenwood and couldn’t be happier. Thanks to everyone for their help!!
Thanks for the follow up. :thumbup:

...

Assuming that it eventually got resolved, it's too bad that the OP didn't get back with whatever they found.

:2cents: vic
We still don't know what the exact issue was, but anyone with similar symptoms now knows that replacing the OEM radio with a 100 buck aftermarket head unit has a very good chance of resolving the problem.

I installed an $89 Kenwood and couldn’t be happier.
...
The OEM Becker radio is not the best. Neither are the OEM speakers. If you haven't upgraded the OEM speakers yet, that improvement to sound quality is also worth the cost/effort.

:cheers: vic
 

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