Electrical gremlins.....and the roof!

[Mike.Gamble]

I've just picked up a Boxster fairly cheap after the previous owner gave up on it!
It's just gone straight through the MOT after the plugs and coil packs were changed which resolved the mis-fire and engine management light issue which the previous owner somehow couldn't resolve.

The only two remaining issues I have to resolve are the rear spoiler does not deploy correctly and the warning light remains illuminated on the dash. I can deploy it manually but the dash warning light remains on. I've heard this is a fairly common problem and was wondering where the best place to start with it was?

And secondly, my instrument panels are not working correctly. The rev counter works correctly as does the oil temp and fuel gauge but the speedo does not work nor does any of the on board computer information such as the range, mpg etc. Any pointers?

 

[Motorhead]

Mike, For starters, if you've not already done it I'd check all the relevant fuses and re-seat any appropriate relays (slot #9 in the rear relay panel): http://www.theschillings.com/boxrelay.htm Other than that, a diagnostic check would at least point you in the right direction. Good luck.! Jeff

 

[Mike.Gamble]

Cheers for the link. I found one missing fuse but in an unrelated system so it won't have any affect on the spoiler. I've checked relays 3 & 9 and both are seated fine. I've just noted that when I use the button under the dash to deploy the spoiler, it goes straight up but, when I want to retract it, I have to keep the button pressed down all the time until retracted. If I release the switch, the spoiler stops coming down. Is it likely that both relays are dead?

 

[Nick_USA]

I've just noted that when I use the button under the dash to deploy the spoiler, it goes straight up but, when I want to retract it, I have to keep the button pressed down all the time until retracted. If I release the switch, the spoiler stops coming down.

This is normal behaviour ..... The down with switch is a safety feature to prevent fingers getting trapped.

 

[Mike.Gamble]

ORIGINAL: Nick_USA

I've just noted that when I use the button under the dash to deploy the spoiler, it goes straight up but, when I want to retract it, I have to keep the button pressed down all the time until retracted. If I release the switch, the spoiler stops coming down.

This is normal behaviour ..... The down with switch is a safety feature to prevent fingers getting trapped.

Thanks for that, it's one less thing to worry about. Just thinking out loud as it were, the spoiler is deployed when the vehicle reaches a certain speed, is that correct? If so, could this some how be linked to the problems with the dash information, etc? Maybe as the speedo, neither the needle of the digital one is working, the correct information is not being sent, hence no spoiler being deployed?

 

[Motorhead]

Yes Mike, the spoiler should be deployed on reaching 70mph+, or there abouts, and then retracts when the speed falls below about 50mph. With all the integrated electronics on-board, it's quite possible that your non-functioning speedo and spoiler problems are related. Unfotunately, I've no idea how you're going to sort that one out without a detailed circuit diagram. As Nick says, you need to keep the button depressed to manually lower the spoiler. Jeff

 

[Richard_Hamilton]

I would check the connector plugs on the instrument cluster. The spoiler relay gets its speed signal from the cluster, so it may well be related. If you drop me an email, I'll send you the instructions for removing the cluster.

 

[Mike.Gamble]

Email sent, many thanks!

 

[Mike.Gamble]

Cheers for the information. I have removed the dash this afternoon and checked all the connections and re-fitted it again. Unfortunately, the problems still remain. I'm going to concentrate on the dash first and see if I can get that sorted in case that turns out to be a contributing factor with the spoiler. Any thoughts,/suggestions where to start with it?

 

[Mark_Bennett]

Given your blocked drains problem in your other post, I'd check under your passenger seat and see if it's wet - the modules under there don't like to be immersed in water can can cause all manner of problems.

 

[Mike.Gamble]

I'll have a look tomorrow and check it's not wet inside. Also, if I plug the car into a diagnostics machine, will that tell me where the fault lies?

 

[Mike.Gamble]

Yes, it's soaked under the passengers seat! I've had a quick look under the seat and can see some wiring into the seat (which I assume is unrelated and relates to the seat electrics?) and then a black module of some description on the floor. I take it that it's a case of seat out and have the unit checked or are there some checks, bypassing it/making contacts etc that I can do? Also, whilst I've got to check the drainage in the front bulkhead, are there any more around the car which I should check to prevent ingress from other areas?

 

[Mark_Bennett]

Ack! That could be expensive [] That's the alarm control module - it could be causing many of the problems you've been getting. The wires to the seat are, as you say, just for seat motors. Yes there are also drains under the convertable roof - raise the roof half way so that the clamshell is open, and you should be able to see a drain each side in the foam liner.

 

[Mike.Gamble]

I've taken the passenger seat out and had a look at the module which, thankfully doesn't seem to have been affected by the ingress of water. I've removed it and popped it on top of the radiator for the evening to hopefully remove any moisture in the unit. Under the carpets, it was absolutely soaking and a great deal of old towels and newspapers were consumed in trying to get it to dry out, I can't believe how much water the sponge base of the carpet retains! I will reconnect everything in the morning and hopefully, I will have resolved the problem but, I'm not going to bet on it!

 

[Mark_Bennett]

Fingers crossed!

 

[Mike.Gamble]

Well, I've re-fitted it and it's made no difference, I still have no dash electronics. I'm getting the car plugged into a fairly top spec diagnostics machine tomorrow so hopefully that may throw something up.

 

[Mike.Gamble]

I've had the car plugged into a Bosch diagnostic system and the only fault code that appeared was 4215, wheel speed sensor, rear left open circuit. I forgot to mention that may ABS light was on as I thought it unrelated and I was going to get it looked at after the other issues had been sorted. It has been suggested that if I rectify this (possibly just a new sensor) it may have an impact on the dash issues depending on where sped sensor is, apparently it is on one the front wheels normally but, as it's rear wheel drive and mid engined, there is a chance that the speed pick up may be on the one of the rears. Any thoughts on this?

 

[Richard_Hamilton]

4215 is "Rear left speed sensor wire *" * = Open Circuit / Short to ground / Short to B+ (12v). I would start by checking the connector. I doubt if it related to the dash issues though. Edit: There is a speed sensor on each wheel.

 

[Mike.Gamble]

ORIGINAL: Richard Hamilton 4215 is "Rear left speed sensor wire *" * = Open Circuit / Short to ground / Short to B+ (12v). I would start by checking the connector. I doubt if it related to the dash issues though. Edit: There is a speed sensor on each wheel.

I'll have a look at the sensor over the next couple of days but when we jacked up that wheel and spun it, there was no indication of a speed reading. I never thought of checking the other 3 at the time!

 

[Richard_Hamilton]

Each wheel has a speed sensor for the ABS/TC/PSM (whichever is fitted). The wheel speeds are compared to determine if one is spinning, locked, etc. The instrument cluster also uses the average of these 4 sensors for the speedometer. If a sensor fails, it uses an average of the remaining 3.