So after researching the light it could be one of two things: Car thinks parking brake is engaged. front brake sensors indicate worn brakes. this is a spider model and with the park brake released it will initiate the top up/down sequence so I can validate the car thinks the park brake is engaged. I’ve removed the electrical connect to the park brake switch under the handle. No change I’ve removed the switch itself too- no change&the light is still on. any ideas on what’s going on with a Park light that won’t turn off?
Assuming an F355 5.2, low brake fluid will also illuminate the light. Since you have eliminated the handbrake switch input, disconnect the sensor on the brake/clutch reservoir to see if the light extinguishes.
Wait, do you have a separate BRAKE and PARK light? I don't mean ABS. The WSM shows this for the USA (F1) car: Image Unavailable, Please Login Only one BRAKE light. Would you have a photo of these lights? Do you have a separate BRAKE light that comes on during engine start?
The BRAKE light will be associated with pad wear and low fluid, so that only leaves the handbrake for the PARK light. All I can think of is that there is a short to ground in the park brake wiring or perhaps the roof control circuitry has a fault. If you measure the resistance of the park brake switch wire to ground, is it zero? I assume it is an orange black wire. Does the roof work? If you run out of ideas, disconnect plug B on the Roof ECU (between the seats) Image Unavailable, Please Login If that fails to extinguish the light, disconnect the roof bypass switch connector. Image Unavailable, Please Login
The manual states that the parking brake should be engaged before the soft top can be operated. Otherwise, I would first check how the parking brake switch normally operates. When the parking brake is engaged, is the switch open or closed? If the switch is designed to open when the parking brake is engaged, and if it fails in its open position, the system will "think" that the parking brake is always engaged and will keep the PARK light "on". In such a case, disconnecting the wires from the switch will make no change, i.e. the PARK light will remain "on".
Correctt, the Pbrake should be engaged but it is not and still the roof starts the cycle. The spider looks at numerous parameters before it initiates the roof cycle and if not satisfied beeps in protest. That does not occur with the brake released. I don’t know if the logic is tied to the illumination of the Park light vs actual hand brake position (on/off). the HB switch is in a very inaccessible position and I can not see it or access it with the brake released unless I disconnect the rear hood latch at the engine. I think the easiest thing is to replace the $2 switch next and see what happens. This model says the BRAKE light illuminates when the fluid is low, not the PARK light. My PARK light is illuminated not Brake light.
Q, The roof works. I did have the roof fluid serviced and then the Park light shenanigans so the connections are suspect!
Maybe a wire got squashed when they refitted the hydraulic block. I'm just hoping they didn't short something out inside the Roof ECU causing the handbrake input to ECU plug B to present a ground to the handbrake circuit. Anyway, you can prove this by disconnecting plug B (the top plug on the ECU)
Understood... I just said this for clarification: But you said you did say you disconnected the connection on it and the problem remained. Open circuit = no light. Don't bother changing the switch.
If you managed to disconnect the wires from the switch, do a test by bridging them and see what happens. If the light goes "off" with the two wires are bridged (simulating closed switch) it would mean that the switch is NC (normally closed, i.e. closed when the HB is released) and that it is probably faulty or needs adjustment. Ian, do you have a detail of how the PB switch is wired on Spiders? My speculation that the switch may operate as closed when the PB is released is based on the logic that, if the connection in the wiring to the switch is lost, or the switch goes bad (open contacts), you will still be able to operate the soft top (especially when it is about to rain).
On USA '97 spiders, the park brake microswitch provides a ground (same on all F355's). The wiring goes to the PARK lamp via splices which also input into the roof system. The instrument panel provides power for the PARK lamp. Does the USA park light show "PARK" or a "((P))" symbol? On my '98 Australian/Euro Spider, I only have a single light for PARK and brake faults. The wiring must all be spliced together, but I've never seen a diagram for it.
I found this on one of your diagrams (extract from Fig 49, "Soft Top Opening/Closing Diagram"): Image Unavailable, Please Login According to this diagram, the HB switch is connected to the Roof ECU and, presumably, it is the ECU that switches the PARK light "on", not the switch directly. If this is the case, then the ECU can be configured to switch the PARK light either "on" or "off" when the switch is in the open position. I see that the HB switch is shown as "open" on the diagram but it does not say whether this is when the HB is engaged or disengaged. I also notice that the the HB switch is shown in a state opposite to what the door switches show. I still think that a test with shorting the two wires going to the HB switch should be performed before digging deeper.
The roof diagram is simplified. It doesn't show the splices. If you also look at the roof diagram, there is another input from the handbrake switch to the roof emergency bypass switches. I wanted to show the splice, but it would involve running a wire from one side of the diagram to the other (messy) Here's a diagram which shows the splice "30078" (near the handbrake switch 03050) https://www.dropbox.com/t/xJzbbBWEIkLLkc7P
I pulled my car to pieces and am getting some strange results... I disconnected plug B on the Roof ECU and probed pin 12 (orange/black wire)... and I'm getting a permanent short to ground, irrespective of the handbrake position. I'm trying to figure out what would give me this. The combined handbrake/brake warning light works normally on my car. On my car, low brake fluid level also puts on the brake light and there does seem to be continuity between the brake fluid level pink wire and pin 12 of plug B. I'm not going to pull my handbrake to pieces to check the switch (because I know it works).
CORRECTION: actually, pin 12 on plug B going to the Roof ECU is 15 ohms with the handbrake not pulled and zero ohms with the handbrake pulled. The same applies to the bypass switches. I'm wondering if I'm measuring the resistance of the BRAKE lamp to earth somehow (I've disconnected the pink wire on the brake fluid level sensor). I don't think that my brake pad wear sensors would generate 15 ohms. The ignition key was turned off. Some of this may or may not be related to Richard's car.
