Intermittent electric hood problem.

[devboy]

I have had a problem with the electric roof, both going up and down. When it decides not to work, it usually won't until I have left it for a while (at times up to an hour). Sometimes I can apply gentle pressure while getting the roof down (foot on brake, finger on button and the other hand applying the gentle pressure). Then it will reach a point almost level with the head rest of the seats and go down at normal speed. When it doesn't work, there is no motor noise.

I've superficially checked for breaks in cables visually and have been unsuccessful in finding any fault there (at present). I know if I do get 'stuck' or rather if the roof does, that I can disengage the motor by turning the key on top. I've looked at the knowledge base on here (which I've found very useful on many occasions, lurker user that I am of this forum), both posts I have found regarding similar problems are avenues I'll explore time permitting but I hazard a guess that it is the motor itself failing. If anyone has reason to believe otherwise, please pipe up!

My total knowledge of cars almost falls into the 'oh that's the blue one' when asked what my car is, so I'm not to be mistaken for being a mechanic by a long shot!

I would welcome anyone's opinion of likely causes. Looking at my motor, it looks like the fluid level is low, having said that it seems the same on this post http://www.zroadster.net/forum/viewtopi ... od#p198221 too (in the knowledge base), so it probably has no bearing on what is happening regards the intermittent nature of the fault. Out of interest, does anyone know what fluid is used and has anyone had occasion to top it up or is it just a case of replacing the motor if that proves to be the fault?

Here's a couple of pix of the motor and the fluid level.

[peterandjenny]

Our roof motor looks very different to yours we have had ours in manual mode for a while , I suspected the roof micro switch but after taking it out today found it was working fine . We have the same symptoms will work most of the time but every now and then it will just stop . Low oil may be the problem looking how to top it up will post if I find out how

[devboy]

Your motor does look very different! Mines a 98 model 2.8, on mine there appears to be a allen key operated aperture located on top of the motor itself, which helpfully I haven't pictured, that I assumed would be for topping up the fluid (from memory anyway), if I find out the cause and resolve it, I'll relay the solution too. Many thanks for your input!

[Robert T]

When you say it doesn't work, what do you mean? Can you hear the pump running or not? If you can't hear the pump then it is likely to be an electrical problem. If you can hear the pump, then it is either mechanical or hydraulic.

Common electrical problems are: the roof microswitch, the arm on the microswitch getting bent, the wiring leading to the roof microswitch, the roof switch on the console, the brake light switch (do you brake lights work?)

Mechanical problems are less common, but it has been known for the top to snap off the ram and for the seals to go on the connections to the hydraulic ram.

In the photos above I would say the the fluid level was approximately correct. The target dot is the level it should be at. There is a lot more fluid you can't see in the pipes and ram itself and it is this that is pumped back and forth. If the level is significantly lower it means that the system has a leak and you need to find and fix that leak - it is a closed system and should not lose any fluid. bonbon had a leak on his and it made a lovely mess.

Cheers R.

[devboy]

When you say it doesn't work, what do you mean? Can you hear the pump running or not? If you can't hear the pump then it is likely to be an electrical problem. If you can hear the pump, then it is either mechanical or hydraulic.

Ahh, then in that case it is likely to be an electrical problem, many thanks, that makes perfect sense now as when it doesn't work, you can't hear the motor or anything else for that matter.

Common electrical problems are: the roof microswitch, the arm on the microswitch getting bent, the wiring leading to the roof microswitch, the roof switch on the console, the brake light switch (do you brake lights work?)

Again, many thanks, that's the areas where I can focus on now then, brake lights work fine so roof microswitch, its arm and wiring, along with the switch on the console are things to look at.

In the photos above I would say the the fluid level was approximately correct. The target dot is the level it should be at. There is a lot more fluid you can't see in the pipes and ram itself and it is this that is pumped back and forth. If the level is significantly lower it means that the system has a leak and you need to find and fix that leak - it is a closed system and should not lose any fluid. bonbon had a leak on his and it made a lovely mess.

Cheers R.

Again, makes sense being a closed system, presumably it wouldn't have means to 'dry out' over the years, barring any leaks of course.

Top man!

[peterandjenny]

Ours does tend to just stop randomly with no sound points to electrics , roof micro switch is ok so is the wires to it, brake lights work ok , works 7 times out of 8 but can just stop. Sometimes after pressing again it will work ! Intermittent problems are a pain .

[kruisn]

Could it be the wires from the roof micro switch shorting out somewhere along the frame? Also you say the switch is working fine, but how do you know that (I have the same problem, it has just stopped this weekend.) Can the micro switch be disconnected from the wire or are they permanently joined. I have seen a posting here where one of our members substituded a similar switch from Maplins for a few quid.

[peterandjenny]

Followed the wire down to the white connector meat the top of the ram and used a multimeter to measure the circuit .all ok do not think it is the switch in the front as it has the same symptoms science putting in a facelift switch for the m console .what next ?

[Robert T]

Just because the wires are making a circuit when the roof is in the up position does not mean that they will be making a circuit when the roof is half way down. The cabling leading up to the microswitch can chafe and break in a similar manner to the boot lid wiring. When it does, the action of lowering the roof can cause the circuit to intermittently break, as the wires flex and bend as the roof folds. If you want to really test that it is not the microswitch and/or its wiring, then you need to disconnect it at the top of the ram and short the pins together. If the fault persists, then it is more likely to be the roof up/down switch.

Cheers R.

[peterandjenny]

Thanks, will try shorting it, it could be the wire but was fine when fully up and fully down.

[devboy]

An update on my particular problem regards the roof and intermittent power getting to the motor.

Around two weeks ago I tried to put the roof down for my return journey from work. It went down faster than I had ever known it, I can't be sure but perhaps I glanced a finger on the switch after the roof was down (in the split second that my foot was still on the brake) and the roof shot up. I do mean shot up, it must have taken at most 2 secs. It's a good job my seats are already brown.

I then tried to open it again, no joy! The motor could be heard still working, trying to close the roof. The only way I could stop it was to take the fuse out. Prior to removing the fuse, I did check the console switch and disconnect it, the motor was still working with the roof already shut but still trying to close the roof.

I replaced the two relays mounted on the motor itself when time allowed and have open and closed the roof at will again several times, without problem. As to this being the 'actual cause' of the fault, heaven knows but it seems to have resolved it for now. If the old fault rears its ugly head again, I'll let you know.

The suspects... for now at least.