Tuscan door solenoid
Discussion
The driver's side door solenoid has been struggling for a while now (taking a few pulses to open the latch), and finally decided to give up the ghost today just after I'd parked in the car park in Kingston...
Long story short, I've removed, stripped and refurbished the solenoid (which it turns out isn't actually a solenoid at all!), using a motor I picked up this afternoon on an emergency trip to Maplin. I've refitted the refurbed solenoid, which now releases the lock completely at the first push of the door release button. A massive improvement in itself, which is a silver lining!
However, I now have a new problem in that after the solenoid has moved to the bottom of its travel, releasing the latch on the door mechanism, it stays there and doesn't return to the starting (latched) position at the top. There doesn't seem to be any mechanical means that I can see to pull the lever arm and solenoid actuator back to the top. Can anyone shed light on how the mechanism is supposed to reset itself after the solenoid has released the latch?
I would have thought the logical approach would be for the door ECU to send a pulse of reverse polarity to drive the motor in the opposite direction, raising the solenoid actuator (i.e. as opposed to using mechanical means such as a spring). If that is how it is supposed to work, perhaps a fuse has blown somewhere which is preventing the door ECU from driving the solenoid motor in the opposite direction? I've checked all the door-related fuses on the board in the driver's footwell and all look to be intact.
Any ideas? The pic below shows the mechanism in its current state, with the refurbished solenoid:
Long story short, I've removed, stripped and refurbished the solenoid (which it turns out isn't actually a solenoid at all!), using a motor I picked up this afternoon on an emergency trip to Maplin. I've refitted the refurbed solenoid, which now releases the lock completely at the first push of the door release button. A massive improvement in itself, which is a silver lining!
However, I now have a new problem in that after the solenoid has moved to the bottom of its travel, releasing the latch on the door mechanism, it stays there and doesn't return to the starting (latched) position at the top. There doesn't seem to be any mechanical means that I can see to pull the lever arm and solenoid actuator back to the top. Can anyone shed light on how the mechanism is supposed to reset itself after the solenoid has released the latch?
I would have thought the logical approach would be for the door ECU to send a pulse of reverse polarity to drive the motor in the opposite direction, raising the solenoid actuator (i.e. as opposed to using mechanical means such as a spring). If that is how it is supposed to work, perhaps a fuse has blown somewhere which is preventing the door ECU from driving the solenoid motor in the opposite direction? I've checked all the door-related fuses on the board in the driver's footwell and all look to be intact.
Any ideas? The pic below shows the mechanism in its current state, with the refurbished solenoid:
Update: I've been doing a spot of troubleshooting this evening, but now have more questions than answers...
The passenger's and driver's door solenoids are different types. On the passenger's side, the solenoid has a white casing and seems to be the following type:
http://tvr-parts.com/tvr-parts/part-details/tvr-m1...
On the driver's side, the solenoid has a black casing and seems to be this type:
http://tvr-parts.com/tvr-parts/part-details/tvr-m0...
I also tried unhooking both solenoid arms from the latch mechanism, while in the raised position, and then manually depressing the arm. On the passenger's side, the solenoid rebounds as soon as pressure is released, suggesting that there is a sprung return mechanism inside the case. When trying the same test on the driver's side solenoid, the arm stays at the bottom of its travel without returning. When I disassembled the driver's solenoid yesterday, there was no sign of any internal sprung mechanism.
So, it looks as though on the passenger's side the solenoid resets itself automatically (mechanical spring), without being driven by the door ECU. On the driver's side, there is no apparent mechanism to reset the solenoid to the top/locked position, so presumably the door ECU achieves this by driving the motor in the opposite direction.
Both door ECUs have the same part number (ME0427), so is it really possible that they could use different mechanisms to reset the door solenoids?
I have also tried swapping the door ECUs around. When the passenger's ECU is connected to the driver's side mechanism, the solenoid drops to release the door latch but then fails to return to the starting position. This would be consistent with the passenger's ECU expecting the solenoid to return of its own accord.
More weirdly, when the driver's ECU is connected to the passenger's side mechanism, bad things happen. The solenoid makes a grinding noise and the connector to the ECU rapidly heats up, which I guess could be caused by the ECU trying to drive the solenoid back to the starting position (top) even though it is already at the end of its travel, meaning that the motor is unable to turn.
Finally, the driver's ECU now no longer operates the solenoid when plugged back into the driver's side mechanism. If the ECU wasn't already fried, perhaps it is now as a result of overheating when I plugged it into the passenger's side connector...
I'm leaning towards replacing both the driver's side ECU and the driver's solenoid and hoping for the best... does anyone have any other suggestions though? Also, if I do replace the driver's side ECU, how can I tell which type of solenoid to pair it with (sprung/unsprung)??
The passenger's and driver's door solenoids are different types. On the passenger's side, the solenoid has a white casing and seems to be the following type:
http://tvr-parts.com/tvr-parts/part-details/tvr-m1...
On the driver's side, the solenoid has a black casing and seems to be this type:
http://tvr-parts.com/tvr-parts/part-details/tvr-m0...
I also tried unhooking both solenoid arms from the latch mechanism, while in the raised position, and then manually depressing the arm. On the passenger's side, the solenoid rebounds as soon as pressure is released, suggesting that there is a sprung return mechanism inside the case. When trying the same test on the driver's side solenoid, the arm stays at the bottom of its travel without returning. When I disassembled the driver's solenoid yesterday, there was no sign of any internal sprung mechanism.
So, it looks as though on the passenger's side the solenoid resets itself automatically (mechanical spring), without being driven by the door ECU. On the driver's side, there is no apparent mechanism to reset the solenoid to the top/locked position, so presumably the door ECU achieves this by driving the motor in the opposite direction.
Both door ECUs have the same part number (ME0427), so is it really possible that they could use different mechanisms to reset the door solenoids?
I have also tried swapping the door ECUs around. When the passenger's ECU is connected to the driver's side mechanism, the solenoid drops to release the door latch but then fails to return to the starting position. This would be consistent with the passenger's ECU expecting the solenoid to return of its own accord.
More weirdly, when the driver's ECU is connected to the passenger's side mechanism, bad things happen. The solenoid makes a grinding noise and the connector to the ECU rapidly heats up, which I guess could be caused by the ECU trying to drive the solenoid back to the starting position (top) even though it is already at the end of its travel, meaning that the motor is unable to turn.
Finally, the driver's ECU now no longer operates the solenoid when plugged back into the driver's side mechanism. If the ECU wasn't already fried, perhaps it is now as a result of overheating when I plugged it into the passenger's side connector...
I'm leaning towards replacing both the driver's side ECU and the driver's solenoid and hoping for the best... does anyone have any other suggestions though? Also, if I do replace the driver's side ECU, how can I tell which type of solenoid to pair it with (sprung/unsprung)??
Update #2 (in case anyone is reading 
):
Got the multimeter out and managed to fit in a quick spot of continuity testing before leaving for work this morning
Turns out there is a fault on the +ve wire somewhere between the connector into the driver's door ECU and the connector to the motor. This would explain why the driver's solenoid is now completely inoperable, regardless of whether I have the good ECU (passenger's side) or the suspected faulty ECU (drivers side) plugged in.
I still suspect that the driver's door ECU is faulty as it doesn't behave correctly when swapped over to the passenger's side. I also suspect that the fault in the +ve line to the solenoid is probably within the ECU plug, which has been rapidly overheating (too hot to touch) while I've been troubleshooting. The control for the driver's window is also now non-functioning, which again could be explained by a fault in the ECU connector.
Investigations will continue this evening - watch this space
):Got the multimeter out and managed to fit in a quick spot of continuity testing before leaving for work this morning
Turns out there is a fault on the +ve wire somewhere between the connector into the driver's door ECU and the connector to the motor. This would explain why the driver's solenoid is now completely inoperable, regardless of whether I have the good ECU (passenger's side) or the suspected faulty ECU (drivers side) plugged in.
I still suspect that the driver's door ECU is faulty as it doesn't behave correctly when swapped over to the passenger's side. I also suspect that the fault in the +ve line to the solenoid is probably within the ECU plug, which has been rapidly overheating (too hot to touch) while I've been troubleshooting. The control for the driver's window is also now non-functioning, which again could be explained by a fault in the ECU connector.
Investigations will continue this evening - watch this space
Do you mean the plug tbat connects directly to the solenoid? If so, mine has two pins rather than three. It is very crusty though!
Having done a bit more investigating, the 'fault' that I noticed this morning turned out to be a blown fuse, number 22 (labelled 'Door Lock (pin 25)'). I've established that plugging in the driver's door solenoid and pressing the door release button causes fuse 22 to blow. This test has proven to be 100% repeatable, as a small pile of blown 10A fuses will attest... I can be a little bit slow on the uptake sometimes
I think that the driver's door ECU has now fried the replacement motor in the solenoid, as the solenoid is still unresponsive after swapping the passenger's ECU across (although fuse 22 remains intact). This in itself isn't conclusive as I took the replacement motor from a budget educational kit from Maplins, which didn't list the motor's DC voltage rating. It did work initially but now seems to have given up the ghost. I've also measured the voltage across the +ve and -ve wires to the solenoid from the ECU - the driver's ECU is putting out pulses of about 18.5V, whereas the passenger's side is putting out pulses of around 15V. I don't suppose anyone knows what the correct voltage should be?
So far, everything seems to be pointing to a fault in the driver's ECU which is causing too high a voltage to be applied to the solenoid, resulting in a crispy motor and/or blown fuse 22. Too much current would also explain the plug heating up. I'm not sure a corroded contact could be the culprit, as presumably a higher resistance would result in less Joule heating (P=V^2/R).
TVR Parts don't have any replacement door ECUs in stock, and apparently it's a 3-4 week lead time once their ECU repair guy gets back from holiday. I don't suppose anyone has a spare door ECU (part no. ME0427) lying around that they'd be willing to part with, for the right price...?
In the meantime, I might try cleaning up the contacts inside the B pillar and fitting a replacement solenoid (only 13 quid from TVR Parts), if only to rule that out as the source of the problem. If the replacement burns out, then at least I'll have only lost the equivalent of 3 pints (at London prices) and I can be fairly confident that the door ECU is at fault.
[edited to correct typos]
Having done a bit more investigating, the 'fault' that I noticed this morning turned out to be a blown fuse, number 22 (labelled 'Door Lock (pin 25)'). I've established that plugging in the driver's door solenoid and pressing the door release button causes fuse 22 to blow. This test has proven to be 100% repeatable, as a small pile of blown 10A fuses will attest... I can be a little bit slow on the uptake sometimes
I think that the driver's door ECU has now fried the replacement motor in the solenoid, as the solenoid is still unresponsive after swapping the passenger's ECU across (although fuse 22 remains intact). This in itself isn't conclusive as I took the replacement motor from a budget educational kit from Maplins, which didn't list the motor's DC voltage rating. It did work initially but now seems to have given up the ghost. I've also measured the voltage across the +ve and -ve wires to the solenoid from the ECU - the driver's ECU is putting out pulses of about 18.5V, whereas the passenger's side is putting out pulses of around 15V. I don't suppose anyone knows what the correct voltage should be?
So far, everything seems to be pointing to a fault in the driver's ECU which is causing too high a voltage to be applied to the solenoid, resulting in a crispy motor and/or blown fuse 22. Too much current would also explain the plug heating up. I'm not sure a corroded contact could be the culprit, as presumably a higher resistance would result in less Joule heating (P=V^2/R).
TVR Parts don't have any replacement door ECUs in stock, and apparently it's a 3-4 week lead time once their ECU repair guy gets back from holiday. I don't suppose anyone has a spare door ECU (part no. ME0427) lying around that they'd be willing to part with, for the right price...?
In the meantime, I might try cleaning up the contacts inside the B pillar and fitting a replacement solenoid (only 13 quid from TVR Parts), if only to rule that out as the source of the problem. If the replacement burns out, then at least I'll have only lost the equivalent of 3 pints (at London prices) and I can be fairly confident that the door ECU is at fault.
[edited to correct typos]
Edited by 8ball_Rob on Tuesday 23 August 22:20
"Do you mean the plug tbat connects directly to the solenoid? If so, mine has two pins rather than three. It is very crusty though!"
^^Yep that's the one!!!
Last poster mentions 'Paul Smith'. I've tried recently to contact him....and then my dash went up to him for repair via STR8Six. Upshot, is that he seems to deal solely with the TVR dealers...and then, requires much prodding. I don't think he bothers at all with private individuals. Both Paul and Cathy Mason are ex-factory, so have a wealth of knowledge on the electronics of the T cars - as well as the test-rigs for problem solving. However, both seem to be giving up on the repair business.
As an aside, I had my heater ECU checked and repaired by these folks http://www.electroversal.com/contactus.php. They did a good job and turned the work around in 6 working days for about £50.
Nick
^^Yep that's the one!!!
Last poster mentions 'Paul Smith'. I've tried recently to contact him....and then my dash went up to him for repair via STR8Six. Upshot, is that he seems to deal solely with the TVR dealers...and then, requires much prodding. I don't think he bothers at all with private individuals. Both Paul and Cathy Mason are ex-factory, so have a wealth of knowledge on the electronics of the T cars - as well as the test-rigs for problem solving. However, both seem to be giving up on the repair business.
As an aside, I had my heater ECU checked and repaired by these folks http://www.electroversal.com/contactus.php. They did a good job and turned the work around in 6 working days for about £50.
Nick
Hi Mike and Nick, thanks for the tips. It sounds as though Paul Smith is probably the guy that TVR Parts use, based on my conversation with them yesterday.
I think I will try fitting a replacement solenoid in the next day or two, and see if that survives! If fuse 22 blows again, and/or the solenoid motor gets fried, then I'll look into getting the door ECU refurbished.
I assume that the door solenoid is rated for 12V DC - if so, it might not last long if the driver's door ECU is putting out pulses of >18 V (not sure of the peak voltage as I didn't have an oscilloscope to hand...).
Perhaps a short term fix would be to wire a resistor in series with the solenoid, with a resistance equal to half that of the solenoid motor - the goal being to have a voltage drop of 6V across the resistor and 12V across the DC motor. Any thoughts from electronics gurus out there?
I think I will try fitting a replacement solenoid in the next day or two, and see if that survives! If fuse 22 blows again, and/or the solenoid motor gets fried, then I'll look into getting the door ECU refurbished.
I assume that the door solenoid is rated for 12V DC - if so, it might not last long if the driver's door ECU is putting out pulses of >18 V (not sure of the peak voltage as I didn't have an oscilloscope to hand...).
Perhaps a short term fix would be to wire a resistor in series with the solenoid, with a resistance equal to half that of the solenoid motor - the goal being to have a voltage drop of 6V across the resistor and 12V across the DC motor. Any thoughts from electronics gurus out there?
Finally, some good news to report!
Having boldly (foolishly?) decided to take the Tuscan with us on holiday to the Lake District, despite the non-functioning driver's door, I was slightly perturbed when we arrived yesterday evening after a 7hr drive only to find that the boot wouldn't open... luckily I had read the history file cover-to-cover when buying the car, and a previous owner had thoughtfully included a printout of the emergency entry procedure. After some faffing (having never actually attempted the process before), I was able to gain entry and get the car unloaded.
I disconnected the boot solenoid and tried plugging it into the connector for the driver's door solenoid - the solenoid operated perfectly, so no problems there. A continuity test with the multimeter confirmed that the switch behind the badge was also functioning correctly. Finally, I measured the voltage across the boot solenoid pins when pressing the badge and found no change, indicating that the solenoid was not receiving any voltage pulse from the door ECU. So, it seemed the ECU disease had spread from the driver's ECU to the passenger's ECU (which controls the boot release). Strangely, the multimeter showed a constant voltage of 1.1V across the pins of the boot solenoid plug, regardless of whether the badge switched was open or closed.
Anyway, the upshot is that after cleaning the plugs to both door ECUs and swapping the driver's and passenger's door ECUs over, everything now seems to be working just fine. It seems that the door ECU which was originally on the passenger's side is no longer capable of generating the pulse to activate the boot solenoid, but the ECU from the driver's side copes just fine.
I'm beginning to suspect that the original cause of the problems may have been down to water getting into the electrics somewhere, possibly the fuse box. With hindsight, the problems started after a couple of nights of heavy rain when I had neglected to put the cover on the car - out of sheer laziness if I'm honest! I only noticed a few days later that the underside of the carpets in both footwells were soaking wet... I think I've learnt my lesson, I'll be more careful about putting the cover on in future
Having boldly (foolishly?) decided to take the Tuscan with us on holiday to the Lake District, despite the non-functioning driver's door, I was slightly perturbed when we arrived yesterday evening after a 7hr drive only to find that the boot wouldn't open... luckily I had read the history file cover-to-cover when buying the car, and a previous owner had thoughtfully included a printout of the emergency entry procedure. After some faffing (having never actually attempted the process before), I was able to gain entry and get the car unloaded.
I disconnected the boot solenoid and tried plugging it into the connector for the driver's door solenoid - the solenoid operated perfectly, so no problems there. A continuity test with the multimeter confirmed that the switch behind the badge was also functioning correctly. Finally, I measured the voltage across the boot solenoid pins when pressing the badge and found no change, indicating that the solenoid was not receiving any voltage pulse from the door ECU. So, it seemed the ECU disease had spread from the driver's ECU to the passenger's ECU (which controls the boot release). Strangely, the multimeter showed a constant voltage of 1.1V across the pins of the boot solenoid plug, regardless of whether the badge switched was open or closed.
Anyway, the upshot is that after cleaning the plugs to both door ECUs and swapping the driver's and passenger's door ECUs over, everything now seems to be working just fine. It seems that the door ECU which was originally on the passenger's side is no longer capable of generating the pulse to activate the boot solenoid, but the ECU from the driver's side copes just fine.
I'm beginning to suspect that the original cause of the problems may have been down to water getting into the electrics somewhere, possibly the fuse box. With hindsight, the problems started after a couple of nights of heavy rain when I had neglected to put the cover on the car - out of sheer laziness if I'm honest! I only noticed a few days later that the underside of the carpets in both footwells were soaking wet... I think I've learnt my lesson, I'll be more careful about putting the cover on in future
Tuscanuwe said:
Wrong way, better find the cause of water ingress.
...
Uwe
Fair play Uwe, point taken! I'll see if I can locate the source of the leak once I get back from holiday, although I guess that might be easier said than done ...
Uwe
There's a gap about an inch long in the seal between the targa panel and the window on the driver's side, so that strikes me as the most likely culprit - although it's not immediately clear how water entering via that route would reach the fuse box. I'll order a new seal and fit it when I get home, will see if that fixes it!
Gassing Station | Tuscan | Top of Page | What's New | My Stuff