I recently bought a P38 from 1998 whit some work all around. I have been trying to get the tailgate to work but no succes, that's why I'm here. The lock mecanism of the tailgate is working because i can manually open it. I have replaced the button and actuator in the tailgate. I also replaced the ECU in the RH front door. If i press the button on the tailgate the actuator gets 6.4 V. What do I do now?
did you see my reply on LZ ?
Considering the reputation for electrical complexity, the tailgate circuit is probably the simplest circuit on the entire car. Power comes from Fuse 15, goes through C306/C806 hiding behind the RH side panel in the boot (where all coloured wires change to white before going to the tailgate) to the tailgate actuator. The other side of the actuator goes to the pushbutton and the other side of that then makes its way to the RH front door latch where a ground is supplied from the CDL switch.
You should see 12V at the actuator without the button pressed but if that drops to 6.4V at the actuator with the button pushed, you have a high resistance joint between the fuse and the actuator. Worst case would be a failing underbonnet fusebox, a splice that has gt wet at some point or best case, corrosion in the C306/C806 connector.
Pete12345 wrote:
did you see my reply on LZ ?
Yes I did, thanks for the quick reply! This is the first running and driving car I have bought, and its a real project. The previous owner has had it for 2 years in witch he made it road going again. before that it has been sitting for 17 years. I live in the Netherlands here aren't that many of these cars available. My goal is to make it fully functional again and then repair it cosmatically. The car hase about 178000km's and drive's like a train.
some other things that are not working at the moment:
- cruise control
- the backlight of the button to change the ride hight (the button with the round symbol on it right to the button whith the 4 different cars), the orange/red light wich is supposed to light when the button is activated also doesn't work
- the backlight of the button from the hazard lights. the orange/red light does work when the button is ingaged.
- the cruis control button is the same story as the ride hight button. none of the lights work.
I've been trying some more on the tailgate.
All of this stuff whith wiring diagrams and stuff is new for me so I don't immediatly know what i'm looking at or for. But the wiring loom from the tailgate is intact. One of the wire's to the actuator gets 12+ V, the other one with the switch on it gets 4,3 or something when pushed. If i understand it right this is wrong and should be 0 and this is the wire I should trace back to the BECM or ground on the RH front door. and what is the CDL switch?
Already A lot of thanks to you guys for helping me out, I think I will be back a lot of times with questions regarding the Electrickery of this magnificent machine.
The tiny little bulbs in the switches are easy enough to change but expensive if you buy the actual ones but you can take them out and replace just the bulb. I'll see if I can find where I detailed which ones you need to buy (I think they were about £3 for a pack of 5).
The wire from the other side of the tailgate pushbutton doesn't go anywhere near the BeCM, it goes directly to the RH front door latch on a Green/Red wire. This connects to the CDL (Central Door Locking) switch inside the door latch itself. If the central locking operates when you push the sill button on that RH door down, then the CDL switch is working so the problem is between there and the tailgate. There is another connector (as well as the one in the RH side of the boot) C301 lurking just inside the door jamb.
When it comes to electrical issues I find it really helpful to print out extra copies of the relevant parts of the circuit diagrams from my PDF format version of RAVE so I have something to scribble on as I go. Notes of voltage readings, where things are and so on.
I actually printed out all of RAVE and slipped the pages into transparent ring binder wallets. This lets me assemble job specific "mini-manuals". Wallets are wipe clean of oily finger marks too. Being intended for computer access RAVE tends to jump around a bit, "see this section..." is a pain when working from the whole thing but easily dealt with when assembling a mini-manual. Complete print out in big binders needs over a metre of shelf space tho'.
I use the same technique for building up an add on manual covering things hoovered up from the internet or forums. Either in advance of a potentially tricky job or when everything comes to a grinding halt half way through needing research before you can carry on. Doesn't always work. Wasted half a day at the weekend trying to re-discover a trick I used 12 years ago and over optimistically thought I'd remember for ever 'cos it's so obvious.
Clive
Hmm, that took some finding as search seems to have a problem in as much as it isn't returning any results prior to this year. But, how to change the bulbs in the dashboard switches.
To get the switches out you need to push them out from behind. Drop the knee panel, undo the 4 screws that hold the instrument cluster surround in and pull that towards you. That will give you access to one of the screws that holds the centre switch panel in place. If you have the original stereo, remove the surround (it just clicks off) and take out the 2 screws either side of the stereo, then you should be left with one more screw on the passenger side and the whole thing will pull towards you and you can get your fingers behind the panel and push the switches out. Once out you can unplug them and you'll see the bulbs on the side of the switches. Turn them anticlockwise and they come out. That then lets you get to the bulbs themselves.
The dash switch bulbs are STC1877 for the orange ones (https://www.island-4x4.co.uk/catalogsearch/result/?q=stc1877) stupidly expensive but the green ones are STC1878 and are even more (https://www.island-4x4.co.uk/catalogsearch/result/?q=stc1878) but are just a plastic housing with a wire ended bulb. The bulbs can be bought from CPC (https://cpc.farnell.com/sli-ebt/7219-004/wire-ended-3mm-12v-1-9-lumens/dp/SC00339) at under £4 for a pack of 5 or Mouser (https://www.mouser.co.uk/ProductDetail/606-CM7219) at roughly the same price but sold singly. I have a feeling that Mouser have a presence in EU too as a friend in France buys a lot of stuff from them. All you need do is unwrap the wire on the original bulb from the housing and pull it out, carefully remove the coloured cover, fit that to the new bulb and fit it into the holder, wrap the wire around the holder (the first time you do it, have two of them out, one to fit the bulb to and one to see how the wire wraps around the holder, and then then snip off the excess wire. The only one that is different is the one for the Hazard light switch as it doesn't have the coloured 'condom' on it, just plain white.
As they say in all the best books, reassembly is the reverse of the above.....
To change the bulb i find a good solution because I already replaced two buttons to find out these did not have working light bulbs in them. So orderd enough bulbs to change all of them if any other button breaks. About the tailgate, I already found the green/red wire and planned on chasing it down. The door does lock when I push the sill button so the CDL switch must be working. Tonight I will trace the wire down and see if it has a bad conection or crack in it.
Wisse
W.Filius wrote:
. . . . . About the tailgate, I already found the green/red wire and planned on chasing it down. The door does lock when I push the sill button so the CDL switch must be working. Tonight I will trace the wire down and see if it has a bad conection or crack in it.
Wisse
Not quite. When you push the sill button down it physically locks the door, and also operates the CDL switch. CDL is normally open circuit when the door is locked, and grounded when the door is unlocked. This is how it provides the ground for the tailgate.
So if CDL switch fails the door will lock, but tailgate will not.work.
But if the CDL switch has failed, it won't cause the other doors to lock.....
So if i understand it correctly, if the cdl switch of the front right door is broken it would not lock the rear left door and the tailgate won’t function? But there’s nothing wrong with the central locking of the doors everything locks with the keyfob button.
No not quite. If all doors lock when you push the button on the top of the door inside the car down, the CDL switch is working. Pushing that button down mechanically locks that door but also operates the CDL switch which signals the BeCM to lock the other doors. Not using the keyfob, that electrically locks all doors and the CDL switch isn't used (other than to enable the tailgate).
Update: The tailgate is working again! When I took the doorpanel of I found the connector to the cdl and also found a connector for the Floor light in the door witch was unplugged. Fiddeld around with the cdl plug and pluggen the light back in tested the tailgate and it worked.
Now I’m still working on the cruisecontrol. I have allready replaced the red relay and module. Fitted a new vacuüm pump and vacuüm line. Could it be the button on the dashboard or the buttons on the steeringwheel witch aren’t working?
At last I also get a default on the dashdisplay, it says that the back windows and sunroof are not installed. And when i shut the car of it says sunroof open. I haven’t taken a look into it but maybe some of you have experience with this.
I must say you guys have allready been enormously helpfull. Thanks!
Wisse
One more question: does anyone have a good adres to buy some new relays. My starter relays broke.
Siemens
V23134-B52-X127
YWB 100 12
12V
The yellow one.
Back windows and sunroof not installed or not set? If they are not set they just need setting. Press the button to wind them all the way down, hold the button for a couple of seconds, then wind all the way up, hold the button again and the dash should beep and tell you windows set. Do the same with the sunroof, wind it all the way back, then all the way forward then tilt up and tilt back down. That should set them.
The relays are nothing special, just standard 30A relays. Better to replace with 40A ones. I use these https://www.autoelectricsupplies.co.uk/p/12-volt-relay-make-and-break, product 140250. For the green changeover relays, use https://www.autoelectricsupplies.co.uk/p/12-volt-relay-change-over product 140251. There is no duty to pay on shipping to EU if the total order value is under £120.