2004 Z4 2.5 Roof Issue: Flashing Red Light Advice Sought

[Z4USAVA]

I replaced the roof motor but am experiencing the dreaded flashing red light on the dash roof controls.

Background - I hardwired the microswitch in the trunk (to bypass the switch) and replaced the entire wiring harness (main and top harness by the windshield) but still no motor engagement from either the main roof motor or the top motor. Research indicates the flashing red light is a break in the harness wiring or roof sensor issues, but with the new wiring harness in place I am now thinking the issue is within the roof control module. I am getting the following fault codes - 1C CVM Switch, convertible top closed, short circuit to ground; 1F CVM Switch, cowl panel locked, short circuit to ground; 22 CVM Switch, cowl panel unlocked, short circuit to ground and 25 CVM Switch, convertible top stowed.

Update: I replaced the roof control module but the top, windows, motors (main and top) don't work. I still get the 1F CVM Switch, cowl panel locked, short circuit to ground fault code.

Any insight provided would be greatly appreciated!

 

[bigwinn]

Looks like you have chased most of the usual demons down already

What I would do next (assuming you have checked the fuses) is use a multi meter to check voltage at each step of the journey with an assistant pressing the button

If I recall correctly the route is from the main distribution board where the fuses are, then to the GM5, from there to the roof control module via the console switch to the roof loom

Onward to the roof motor, loom and front motors

That’s what I’d do anyway- I’m sure someone else may suggest otherwise

 

[Z4USAVA]

Thank you for your suggestion!

 

[Jas- USA]

I believe you advised you installed a new wiring harness which run thru the roof to the front sensors? If so, I recall a posting a few years ago, (may have been on here or one of the USA Z4 forums) of another poster who was having similar issues after changing out the wiring harness in the roof to the front sensors. He, the poster, solved the problem. I guess he retained the original package and went back thru it. Anyway, there was written somewhere " may require a pin change". He advised which pin it was, but after a few years I'd only be guessing at this point.
Anyway, he changed out the pin and was good to go. Hope this helps.

 

[Z4USAVA]

Thanks, is this the posting you're referring to:

https://www.bimmerforums.com/forum/showthread.php?2437629-2004-E85-top-flashing-red

05-02-2021, 06:39 PM#21Fudged Posting -

I just noticed this on parts site....

"Check X201B plug connection!
Line black/red must be on pin 4
If not, please repin"

He said he repinned the connector and it fixed this issue. I repinned my connector today placing the black/red wire (from Pin 3 slot) into the Pin 4 slot; and switched the wire from the Pin 4 slot into the Pin 3 slot. Unfortunately, it didn't work and caused an additional fault code. I am back to square one.....

 

[Jas- USA]

Yea, that's it, wish it worked.

 

[Z4USAVA]

Yes, me too!

 

[Z4USAVA]

Update: I determined the 1F CVM Switch, short circuit to ground, occurs on Fuse 31 which controls the convertible top. I downloaded a wire diagram of a BMW Z4 2003 and have been testing each module and wire for continuity. I found that there is no continuity on the K-bus connection (14 wht/red/yel X13037) wire from the Convertible Top Module (behind the driver's seat) to the K-bus connection on the Instrument Cluster Control Module (under the passager side dash) (14 wht/red/yel X11175). The wire diagram indicates it is a straight connection between the two modules. Any insight on how to locate where this wire is grounded on the harness? Thanks

 

[Z4USAVA]

Update - If you replaced the main wire harness from a 2004-08 Z4 convertible motor to the cowl motor (near the windshield) with a new BMW harness (Part# 54-34-7-043-906) you may get the following error codes (1C CVM Switch, convertible top closed, short circuit to ground; 1F CVM Switch, cowl panel locked, short circuit to ground; 22 CVM Switch, cowl panel unlocked, short circuit to ground and 25 CVM Switch, convertible top stowed). If so, you need to re-pin the connector near the cowl, it has 4 slots with only three connecting wires. Move the black/red wire to the 4th slot from the 1st slot - when doing so you will notice that on the new harness connector the 1st slot has no male connection; switching this wire should eliminate the error codes and allow the roof to function correctly.

 

[BumpyZ4]

Thanks for the follow up post. It's always nice to get the final fix.

 

[Z4USAVA]

To all Z4 owners with a Flashing Red Light on the control panel...............

BMW convertible roofs on the 2004-2008 Z4 are complex in design and function. I have spent over a year rebuilding the roof on our 2004 Z4 2.5. The last issue I have faced was a fully operational roof that would not lock at the front cowl by the windshield or unlock in the back when collasped. The cowl should automatically unlock in the back when closing the roof (of course you can manually unlock the cowl in the back). My problem was the two roof locks (Part# 54347043873/left and Part# 54347043874/right) in the compartment underneath the roof canvas near the windshield. The hooks on the locks (which secure/lock the roof to the windshield frame) need to fully collasped to a L-shape in order for the roof to be fully secured and locked. The hooks on our Z4 would collaspe partially resulting in a flashing red light on the panel and an unsecured roof. The solution was replacing the locks and adjusting the hooks. Problem solved.....