Since 2003, a series of articles were freely published on the Peugeot Cabriolet Owners Club website providing technical guidance and other useful information.
These articles are then illegally reproduced and sold on eBay as a PDF guide. So, to help owners of 306 Cabriolets all over the world live with their chosen ride, this PDF is now published for free here - exactly how the original authors/contributors intended!
Thanks to all those who produced the original material for these articles (see www.pcoclub.org/articles for full details and additcional articles).
|Please note that neither the author nor the Peugeot Cabriolet Owners Club can guarantee the accuracy or consequences of any article published within this document. Use of any information published in these pages is entirely at your own risk.|
If the electric hood is an important advantage when you own a 4 seater cabriolet, it can also become your worst nightmare when it takes it into its head to work only when it wants to, or quite simply goes on strike.
This is often just the beginning of the battle for the owner. Firstly, there's nothing pleasant in finding yourself with the hood stuck down, or worse still, being unable to lower the hood. Next, you have to repair it. This is the moment when you realize that the manufacturer's dealers are often under qualified on the subject and exploit the situation to charge for replacement of the main parts which are prohibitively expensive. It isn't unusual to hear of a cabriolet owner faced with an estimate for repairs running from €1000 to €6000, which is madness in relation to the value of a car which is not brand new.
I mention the subject because I have personally been a victim of the problem and refused to be fleeced. At that time I owned a 306 Cabriolet and was told I needed a replacement control box (€1000) as well as a hydraulic pump (about €4000) in addition to labor. Since I don't like being fleeced and incidentally am qualified in industrial computing, I decided to analyze the management system of the hood, in order to find the fault and be sure of what needed to be replaced.
After two days analysis and creating a wiring diagram for the hood, since nothing existed on the subject, I arrived at the conclusion that it was the control box and nothing else that was unserviceable. Following this and being highly motivated to avoid giving money to the people who had decided to con me, I started making my own hood control box.
Since that time I have helped numerous 306 owners to solve their problems at a lower cost, but since I can't help everyone, I decided to publish for you a series of articles to give you the means to understand or possibly to solve the problem.
In this article, which like the others, deals with a 1994 model 306 Cabriolet, you will discover the essentials of an electric hood mechanism, together with the most frequent problems that can upset the cycle of raising or lowering the hood.
The first thing to realize about and electric hood is that it is not just electric. In fact, electronics comes into it more for the command software than for the movement of the hood itself. The effort required for moving a hood, and especially its very heavy cast iron frame, is so great that it cannot be provided directly by a 12 volt motor. The movement of a hood makes use of technology rather like that of power assisted steering - namely hydraulic.
It is hydraulic rams, which under the action of oil at high pressure (60-70 bar) that have the task of moving the frame of the hood and its ancillary elements.
When you activate an electric hood (better described as an electro-hydraulic hood), the hood controller (3) first of all ensures that all the conditions are correct for the movement to be initiated, then activates the power relay (2) which in turn activates the electric motor (1) of the electro-hydraulic pump (4).
The hydraulic pump driven by the electric motor puts oil under pressure and this remains captive until the controller (3) activates one of six solenoids (valves) (6) and allows oil to flow under pressure towards one of the hydraulic rams (8) via hoses (7). The pressurized oil pushes the piston of the ram in one direction or another (according to need), and it is the piston which moves the hood.
As has been shown, there is nothing miraculous in the hydraulic mechanism. Like all mechanical devices, it can break or develop a fault, but it is essentially a fairly simple concept and therefore reliable. In view of the short and infrequent use it is subjected to, it really has little chance of being the cause of a problem. Apart then from a fractured hydraulic hose (nevertheless frequent on the 306, see the other articles on the subject), the mechanical side of things is really unlikely to give you any cause for concern.
The majority of problems stem in fact from the electric or computerized control. In fact, if the hood control unit decides to give up the ghost, however much you press the hood button, nothing will happen. Not even a little electric motor noise. And the control unit has many good reasons to be driven into immobility. Since its job is to operate the correct valve at the right moment, it needs to know perfectly at all times the position of the hood and its ancillaries and also that the conditions for safe operation are true.
If, at any given moment, it receives wrong information from its sensors or no information at all, it will put itself into safety mode and will refuse to initiate the operation of the hood or will stop in the process.
The origins of these breakdowns are most often due to:
The first thing to do, therefore, before starting a long investigation of the breakdown is to pursue these three lines of enquiry. To do this, start by a visual inspection of the electrical loom of the hood, looking for any trace of damage caused by abrasion or cuts and paying particular attention to the wires that go up from the base of the hood towards the leading edge of the hood on the right-hand side. This is a wire that often gets pinched by the frame of the hood.
Next, with the help of a contact spray, clean all the connections, principally around the valves and the hood control unit. Check also the tightness of the connectors around the valves.