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      11-12-2020, 03:01 AM   #1
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Drives: BMW preLCI E91 330D
Join Date: Nov 2020
Location: Europe

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Cruise control Retrofit issues with SZL


I am a bit of a beginner, then it come to cars and coding, but I decided to retrofit cruise control to my car.

Just letting you know from the start, that I did tried to search online and on this forum, but I did not find anything like my issue online.

I have BMW e91 (wagon) pre LCI 330d LHD Manual and I am trying to retrofit cruise control that only keeps the car speed steady on motorway (no dynamic cruise control or active braking). My old SZL wiper arm has rain sensor and back window wiper funcition. Also I have active steering.

I read up online that I need new SZL (Steering Switch Unit) that has cruise control arm on it and lower trim piece to fit the new control arm.

So I ordered used SZL online from similar car (BMW e90 (sedan) 330D RHD Manual with same engine power), it had wiper arm that does not wipe rear window, so I switch that arm from my old SZL and by following tutorial online, I also changed Coil spring from new one to my old one.

After removing my old SZL and putting new one on, I noticed that my wiper arm and light indicator arm is no longer working. Wiper arm does not work when you pull it or push it in any direction and light indicator arm does not work in same manner. The only thing that works from these two arm are the BC button with the scroll wheel on light indicator arm and rain sensor activation on wiper arm.

Also after putting everything on I had alot of erros (DTC, Steering wheel !) and noticing that the arms are not working properly I thought that it needs just coding. So I started up my laptop, I added Cruise control option (TEMPOMAT) to Kombi trough NCS Expert, then I added $540 VO to CMS and FRM by adding VO and running FA_Write on CAS. Then I also reopened NCS Expert and selected DSC and ran Sg_Codieren. Then I still had error, but I when to Tool32, selected my DSC_87 and ran lenkwinkel_dsc_abgleichen.

After all that, my SZL control arm are still not working, I can't activate high beams or turn on turn signal (but my hazard lights work) and I can't turn on front or rear window wipers. Also I still had same error, but because I have active steering I knew I had to turn steering wheel from one to another side and go for a short drive, so I drove in small parking lot for a bit and then turn off and on the car. Now it does not display any errors on dashboard, but SZL control arms are still not working. Didn't test cruise control, due to turn signals not working, therefore I didn't wanted to go on public road.

I was following retrofit guide from YouTube, he retrofitted and coded cruise control on his Z4, the only difference I had that when adding VO I didn't had few options to code VO and I didn't had ZDSC so I use DSC and for Tool32 I use DSC_87 and not DSC_89.

Has anyone encountered this issue and knows where the problem is? Maybe I need to program something additionally or my SZL is faulty?

Thank you in advance


Errors I get in INPA:

Video showing problem with SZL arms:

Last edited by Tomas321; 11-12-2020 at 03:21 AM..