Terminal 58s Fault - Buttons and vent dials not illuminating

[darren.kellum]

Hi guys
I have a Terminal 58s fault that is stopping certain dash/MMI/air vent dials from illuminating when its night / turn the head light switch to Auto or beyond.

Its driving me crazy - please see the thread I posted in the Telematics area and let me know if any thoughts?

Link to Thread in Telematics area

Thanks

[Smac770]

I would never know of any follow up in Telematics as I never look there, so I'll post here.

Obvious first step is a full scan for DTCs. The J519 likely already has a code to give some insight.

The J519 puts out Term 58ST (parking lights on and ignition on) on T32B pin 1. This just goes to the E408 ignition start/stop button and the gear selector lights.

The J519 puts out TERM 58S (parking lights on) on T32A pin 31 and T32B pin 17. These power:

T32A pin 31:

L67 left dash vents illumination
E102 manual headlamp range control adjuster (non-US)
L68 center dash vents illumination
E149/E256/E266 rear window shade button / ESP button / parking aid button - if in the dash ie car has MMI
L69 right dash vents illumination
E536 valet button (glove box)

T32B pin 17:

LEDs in the front overhead
E139 sunroof controls
E284 HomeLink buttons
E317 interior lighting selection switch (on/off/door button)
E454 left rear reading lamp switch
E455 right rear reading lamp switch
E457 left front reading lamp switch
E458 right front reading lamp switch

E149/E256/E266 rear window shade button / ESP button / parking aid button - if in the console ie car does not have MMI
E538 e-brake button
E693 stop/start button (non-US)
L28 12v socket illumination, dash
L42 12v socket illumination, console front and console rear
L93 rear temp selection switch
E128 left rear heated seat switch
E129 right rear heated seat switch
R126 telephone base plate (non-US)

You see the T32A/31 powers stuff along the front dash center line. The T32B/17 powers the overhead and the center console.

But is it a device on the line overdrawing current? Is it a short of a wire to the chassis? Is it the driver circuitry in the J519 dying?

You comment about the lights on the E1 exterior lights switch. Term 58S and 58ST are both PWM signals on those pins, as well as bus signals to other modules. The E1 light switch is connected via LIN bus to the J519; it's likely getting a command for dimming illumination rather than passively controlled by the Term 58S PWM signal. There's also the Term 58D which is just a bus signal to other modules also.

[darren.kellum]

Thanks for this detailed reply. These items are certainly all the ones not illuminating across both the 32A and 32B.
I didn't check pin 17 of the 32B yet so will see whether that might be loose or something.

For a moment I thought it could be because I have just set 3 new wires into 32A for a Valet switch retrofit (one being a splice into 31). I activated the function via ODB Eleven but haven't received the switch yet to plug in so thought perhaps it just didn't like the open connections. I just deactivated the function and cleared the 00379 Terminal 58S fault code but it didn't make a difference and returned when I turned the headlight switch again.

When I turn the headlight switch I hear a very faint electrical squeal noise which then fades out. Its so faint I cant yet work out where its coming from but certainly down the driver footwell or door card. I think if I can go out when its deadly silent outside (unlikely on my busy street) then I may just hear where the noise is and could lead to the issue.

[darren.kellum]

Ok case closed - I pulled the MMI DVD unit out and retraced my steps with wiring I had done for the Drive Select Switch retrofit. Unwrapping some of my wire tape I saw that the 58s signal wire had some exposed wires where I had attempted a splice in the past. That was touching a slightly exposed earth wire splice I had used for the switch. I should have shrink wrapped properly but did it in a rush and this was the result, hours of wasted time. Lesson learned.. do the job properly first time!
Anyway, all working now, code cleared for good.

Thanks again for your help!