# x5m electric tow hitch retrofit coding help



## gmk2 (Feb 25, 2017)

Hi there,

Reposted from BMWcoding... its very quiet over there (hope thats ok).

I have retrofitted the electric pivot-mounted trailer tow hitch (part 71 60 6 797 619) with retrofit kit 71 60 2 166 385 on a Dec 2012 build X5M. The car is on the edge of the LCI update and came with some of the LCI features. Note: In Australia we use the euro trailer light requirements rather than the north american - so have not considered +AHMU

First step I got the tow hitch fitted and all the wiring now in place - its pretty involved with this hitch!

The retrofit instructions unhelpfully suggest I "Program/encode the retrofit with ISSS (Integrated Software Service Station) via the –Conversions– - path"

What I have done is set up NCSExpert with V60.1 daten. INPA connects fine with the car and I can see the two black dots and read error memory etc.

I found a number of guides recommending to update the vehicle order, so I reviewed the vehicle order options and it appears 3AC is the one I need for this hitch.

I worked out that CAS and FRM were the two central units for the vehicle order. I have added 3AC to both of these and done an FA_Write. I can see the 3AC now listed. At this point I only updated these modules and did not process car.

I then could see the AHM module. However - nothing works. The button to operate the hitch however is not lit up and pressing it does nothing. The car starts and runs as normal with no errors or warning lights.

I had a look with INPA and the AHM module is reporting error AAAF 68 (and apologies I still can't work out how to translate this). I'm not sure what this means.

Next step: I attempted to 'process car' after this, a number of modules updated before hitting an error on DWAS: "ECU does not answer IFH-0009: No response from controlunit SINE_65". NCS Expert then resport "Coding is Faulty" with "DWASINE.C05, A_E65.IPO, SINE_65.PRG"

Manually updating individual modules using sg_codeiren with the updated VO worked on AHM, KOMBI, CIC and I didn't see any other failures.

After this, the button for the towbar still remains unlit and does nothing, car continues to start and run normally with no errors.

Any tips on why I get this error on 'process car' or is there a view on which specific modules need to be sg_codeiren to activate the tow bar?


Thanks!


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## gmk2 (Feb 25, 2017)

UPDATE:

Came home and after the car sitting for 24h and mysteriously its now showing an error on ignition - it now shows "Trailer tow bar electrics failure"

So at least some of the update appears to be sticking. As an example, I can see if I go to the reverse camera the option to engage the trailer macro zoom.

So - onto diagnosing the issue. I tried running the INPA diagnostic on the trailer component and I get an interesting error: "Requested control unit: 'AHM_E65' not found. Control unit found: 'AHM_70'. Program will be stopped!"

So it seems that its expecting me to have a different version of the module? Is this perhaps a daten issue of some type - perhaps the VO I coded defaulted the wrong module?

Help greatly appreciated!


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## mr_nitroz (Dec 16, 2015)

I made this retrofit without any problems, there are 2 modules main is AHM and second for operating of towbar. Second unit is connected with AHM module thru LIN bus and only AHM unit can be coded. Check if you have AHM unit version 4 as only this can comunicate with second unit. And check all fuses and ground points if are connected properly. Button have a LED light that is green if all is OK or red if there is some problem.


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## gmk2 (Feb 25, 2017)

Thanks for the response!

The AHM unit came as part of the wiring retrofit kit - all part numbers were triple checked before ordering. In terms of actually checking the version of the AHM I'm not clear on how that would be done - as noted earlier my INPA install currently won't run a diagnostic on the unit which I am suspecting is possibly something wrong in my install / configuration but not sure how to validate this.

I will have another check of the wiring to the fuse panel - this was the most suspect part of the install for me as pushing the wires into the socket casing from the back they didn't seem to 'lock in' with any degree of certainty. Maybe I need to remove the socket casing from the back of the fuse panel to get them to fully engage before putting the terminal.. The button currently is not lit at all - I was unclear if this had a dependency on coding being correct or only on wiring.

I'll have a look either way tonight when I am back home.


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## mr_nitroz (Dec 16, 2015)

It is written right on the AHM module. But you should have the correct one and there is different connector for module.


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## gmk2 (Feb 25, 2017)

SORTED!

The issue was one of the retrofit wires wasnt seating into the existing socket in the back of the fuse panel properly - this is the 10 pin socket that seems to be different to the others. I had to pull the socket from the panel to get the bastard in and it noticeably 'clicked' into place.

Once this was done I have the light on the button and no errors reported by the car. Pressing the button the tow ball starts to swing out... and I hit my next issue 

For Australia our towbars have to have a point for trailer chains to be attached. I know the BMW Australia imports the euro towbar and welds on attachments for this purpose. I did exactly the same thing without having seen exactly how BMW do it.. however the clearances when the tow ball swing out are so small that the tiny tabs I had welded on foul the car.

At least this is a straight forward meat and potatoes engineering issue now!

Thanks for the help mr_nitroz.


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