2002 Honda Jazz Sunroof Issue

[bumblebee]

Hi there,
 
I’m having issues with my sunroof and thought i’d ask the community.

Every time I turn my electrics or engine on the sunroof automatically goes fully back/open. The switch is somewhat reactive, when i press close it stops it going backwards until i take my finger off. It then won’t close at all and i have to manually wind it closed when i’ve finished driving with a hex key in the sunroof motor.

It was having this issue for a while but then resolved itself after a few drives. Then I had to change the battery for a new one and it got worse (doing it every time). I understand sometimes disconnecting the battery can cause issues. I checked inside fuse box and 19 (sunroof) fuse was missing. I put a fuse in then but still need to try few different amp ones (not sure which it is meant to be). I also bought a new (spare) switch on ebay. I have checked the tracks and no obvious obstructions, and applied new silicone grease to help.

Any thoughts on this, what may be the cause/solution? Any help much appreciated, thank you!

It also sounds like it’s trying to draw power from the battery every now and then. I can hear less power in the engine and the sunroof motor makes a click type sound.

[Marco1979]

Sounds as if the switch or another part of the sunroof motor causes a short somewhere. Check for corroded connectors or moisture. Strange that the fuse was missing; that might be an old fix?

[Lord Voltermore]

It may not be much help but when I tried  looking up fuse values for sunroof I only found it for a US spec Fit/Jazz   .  And this had 2 fuses.  a 7.5 amp one for  the sunroof control unit and a 30 amp one for the sunroof motor.   

Its not surprising the motor needs 30 amps.  But 30 amps also requires  a heavy duty switch.  Cars normally minimise how much heavy 30 amp wiring is required  ,and avoid hefty switches in the cockpit , by using a low amp switch and wires  to operate a remotely located  relay switch . (often located in fuse boxes)   Relays are basically a  heavy duty switch , which is switched on and off by a lower amp switch and wiring circuit. 
 
Neither the relay  or the motor itself should have worked  at all  if  their respective fuse was missing.

I agree with Marco that the sunroof may either getting power from another source due to a short circuit,  or possibly  a previous owner tried to fix  it by modifying wiring, connecting to another circuit etc.  And if its intermittently getting power from both sources at the same time  this may account for its erratic behaviour.   

Sorry to say this  but both scenarios could potentially be dangerous.  And needs further  investigation.   If the motor is trying to draw 30amps through wire that is too thin the wire can overheat and  cause a fire.

Faulty wiring ,switch or relay might also have added to  the parasitic drain on your old battery and hastened the need for it to be replaced.   The new battery may have changed behaviour a bit by  providing more power .   . 

[bumblebee]

Thank you for your replies, really appreciate it.

From what you’ve said it sounds like it could be that. I’ve now added the 7.5 amp fuse into slot 19 and after a journey or two it’s now working, staying closed and operating (not sure how exactly). Although I am a little worried about your comment on the short circuit possibly causing further issues/fire if wrong wires are used/too much power. Is there any way of finding out what someone may have altered or testing the currents?  how to properly fix the possible short? In my jazz the motor is located just in front of the rear roof light, I can’t see a way of investigating the area without taking the entire head lining off or cutting a small area of it around the motor.