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George Member
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Hi guys. Got my JH5 back on the road yesterday. Great fun. But (there is always a but) while off the road I replaced the brake hoses and a couple lines and now the brake light stays on, even though the brakes are working great. Is there something I am supposed to have done to the brake pressure thing near the master cylinder, or is this some annoying electrical problem I will need to sort out? Thanks for all the help past and future. george |
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Mitch Ware Member 
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Unplug the wire from the top of the PDWA and see if it goes out. If so, then there was an inbalace in the lines when you bled the system and it shoved the piston to one side and closed the circuit which turned on the light. Mitch Ware 1974 JH-5 #111119670 1971 TR-6 #CC66950LO |
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George Member
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Thanks Mitch. The light does go out when unplugged. Knowing it's called a PDWA, I was able to search the archives and learn how to try and recenter the switch. May give it a shot someday. |
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Harkes Member 
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hi guys, i seem to have a similar problem. My Brake Park Fail light stays on when ignition on and hand brake is released. i disconnected the PDWA and Brake Park Fail light goes out... Funnily enough when hand brake is engaged the Brake Park Fail light does NOT go on either.. I did fiddle with the wiring of seat belt warning lights; does this have anything to do with it? How to center the PDWA?? (i can't find it on the message board) and any ideas where to look for regarding the hand brake? thanks Erik |
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Harkes Member
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i was just thinking; i changed to a TR6 M/C and all new brake pipes and the Jensport Big Brakes. can bleeding the brakes, when one has changed/renewed the whole system, cause imbalance ? Since i only bled the front brakes and not the rears as yet...when done will the imbalance dissapear or how does this work? thanks erik Last edited on 07-10-2006 03:22 pm by Harkes |
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George Member
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I ignored my brake light issue, then ended up having to change the master. After I replaced it, the light was out with no balancing neccessary. |
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Mark Rosenbaum Member 
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Harkes wrote: My Brake Park Fail light stays on when ignition on and hand brake is released. This is a fairly conclusive indication that the little piston inside the PDWA is now off-center. It's also possible, but unlikely, that the PDWA switch itself has failed in some way. Harkes wrote: Funnily enough when hand brake is engaged the Brake Park Fail light does NOT go on either.. I did fiddle with the wiring of seat belt warning lights; does this have anything to do with it? There are two switches in a single case, that are operated by the hand brake. One section works in parallel with the PDWA switch, so that if either or both is closed, the Brake Park Fail light will illuminate. The second section of the switch is connected to the Infamous Seat Belt Warning Module. It's quite easy to hook up the switch wiring incorrectly, and that may be what's happened in your case. Unfortunately the handbrake switch is perhaps the least accessible electrical item in the entire car. Harkes wrote: How to center the PDWA?? (i can't find it on the message board) [...]? Since you bled the front brakes only, most likely pressure in the rear brake lines moved the PDWA switch piston off-center. Bleed the rear brakes, and pressure in the front brake lines should move the piston back to center. If it goes too far, loosen the front brake bleeder slightly and have someone slowly apply pressure to the brake pedal until the Brake Park Fail light extinguishes, then re-tighten the bleeder. If you are unlucky, you may have to apply this process alternately to front and rear brakes, repeatedly, until the switch ends up centered again. Attachment: pdwa disassembled x2.jpg (Downloaded 81 times) |
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Harkes Member
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Thanks Mark, The PO had switched off the Infamous Seat Belt Warning module by connecting the wires that go to the seat and to the seat belt to each other... I will make a picture of it and show you. now i don't know whether this is good or not, but before i started taking the car apart it all worked fine (meaning no seatbelt warning whilst in seat without seatbelt strapped and car started). Also with the handbrake engaged the Brake Park Fail light would switch on and off when released again. since i yesterday bled the rear brakes i don't see any Brake Park Fail light which seems good now then. But i'm getting a funny feeling that may be something is not good. Where should i start; since i did start fiddling with the wires that go to the seat and seatbelt i might i have changed things because of which now things don't work? The rear lights work fine when lights are switched on, right rear flasher light works fine, back-up/reverse lights work fine and when braking using brakepedal the brake lights go on as well. But the left rear flasher light doesn't work whereas i checked the bulb is fine. I need to change the right front headlight (high beam works but not the regular light) and the horns don't work.. The interior light in the door worked for one minute then ceased... lord lucas striking? i need to take the car for MOT so the flasher light, horns and headlight must work. thanks for your help, very much appreciated. erik Last edited on 07-11-2006 08:38 am by Harkes |
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Mark Rosenbaum Member
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Harkes wrote: The PO had switched off the Infamous Seat Belt Warning module by connecting the wires that go to the seat and to the seat belt to each other... I will make a picture of it and show you. [...] Where should i start; since i did start fiddling with the wires that go to the seat and seatbelt i might i have changed things because of which now things don't work? Those wires go only to each other and the seat belt module. Unless you connected them to some other circuit, or you have really severe wiring problems, it's highly implausible for them to have anything to do with your problems. Harkes wrote: The rear lights work fine when lights are switched on, right rear flasher light works fine, back-up/reverse lights work fine and when braking using brakepedal the brake lights go on as well. But the left rear flasher light doesn't work whereas i checked the bulb is fine. Apparently the ground connections are all good. Does the left front flasher work? If not, check the turn signal switch for one or more bad wires or connector pins, or bad contacts inside the switch. If so, check the socket for the left rear bulb and ensure that the spring-loaded pins that make contact with the bulb base are clean and can move. Reassemble with a small amount of dielectric grease applied to the electrical contact areas of both bulb and socket. Harkes wrote: The interior light in the door worked for one minute then ceased. Is the bulb still good? Are the contacts inside the light housing still in good shape? Has the light housing melted or distorted due to heat from the bulb? Is the switch in the correct position (it has three: always off, always on, and on when door is opened)? The switch receives its power directly from Fuse #3 so check the fuse and the wires connected to it. Harkes wrote: the horns don't work Check the various bullet connectors in the wiring at the front of the car. (If these are not making good contact, this could also explain your headlight problem.) Check the wires and connector pins for the turn signal / horn / headlight switch. The horn switch itself is inside the end of the turn signal lever. The cap unscrews and you can then examine the contacts. Inside the switch, the body of the lever is connected to the wiring via a rather fragile crimp connection. It is sometimes possible to repair this connection if it is broken. Since a replacement switch is very expensive, a repair is always worth attempting. Harkes wrote: lord lucas striking? No. It's hard to tell in these multi-national days, but I think he's actually working for me in some subsidiary position at the moment. :^} |
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Harkes Member
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Thanks Mark, time to trace the wires with a meter and see if there is a current or not. nice job for the coming weekend. I want the shark on the road (legal...) thanks i'll keep you posted. erik |
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Harkes Member
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Hi Mark, i found out few of my problems where due to a blown fuse (bottom fuse)....should have looked there first as you explained in your reply. New fuse and voila, my horns and interior light are both functioning well the right headlight problem was due to a broke wire...easy to trace. The left rear flasher was a grounding issue. NOt in the wires though but in the foot where the light bulb sits. Little bit of solder solved the issue. so ready for MOT now. One question left concerning hooking my stereo: i need to connect to 12V (for stereo memory) and 12V switched. Now i read on John Kimbrough's website that 12V switched can be found on the ignition white/blue. I found that wire in the dash behind the stereo (don't know its function??). But my problem is finding a 12V for the memory which will not overload the fuse! So i was thinking: why not combine the red 12V switched wire with the yellow 12V wire of the stereo and connect it straight to the battery +? Thanks as always. erik |
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John Kimbrough Member
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Erik, if memory serves me, I connected my memory voltage to the cigarette lighter wiring. It was always hot and it runs right through the general area. John. |
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Mark Rosenbaum Member
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As John mentions the cigar lighter wiring is a good source of power for a stereo memory. For the switched power, the ignition switch has an ACCESSORY position that is generally used to power a factory stereo. Given the limitations of the ignition switch, it would be prudent to connect this to the coil of a relay, whose contacts would switch power directly from the battery through an inline fuse. This would allow lots of current for a modern, high-power stereo, without overloading the existing wiring. You could also power the stereo memory via the wire from the battery. This arrangement allows stereo use only if the ignition switch is in the ACCESSORY or RUN positions. I've attached a simple drawing which may clarify things somewhat. Attachment: STEREO.jpg (Downloaded 309 times) |
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John Kimbrough Member
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Mark, I like your idea of isolating the stereo amps from the ignition switch. May do that myself. Just hate the thought of pulling out the console again though...... John. |
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Harkes Member
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Hi Mark, thanks. This is exactly what i had in mind. The ignition relay idea is a very good one, i hadn't thought of. regarding the inline fuse wire from battery to stereo; how much Amps would you reckon is necessary? I need to get a 30Amps fuse for the 3rd/lowest one, which was blown, might as well get the wire with inline fuse while i'm at it. thanks erik |
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Mark Rosenbaum Member
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Eric, What fuse size does the stereo manufacturer recommend? Use a fuse of that size. (You'll also need to determine whether they are talking about the must-carry rating or the must-blow rating of the fuse). Lacking the manufacturer's recommendation, you need to know how many watts of sound, total for all channels, the stereo delivers. That, and the stereo's efficiency, will determine the current requirement. Assuming 50% efficiency is a good place to start: while a fuse may occasionally blow if the volume is turned up high, you are also reasonably well protected against wiring and equipment faults. Example: 120 watt stereo. Divide by efficiency of 50% or 0.5 = 240 watts. 240 watts = 12 volts x 20 amps. You would start with a fuse having a must-carry rating of 20 amps. The stock JH fuses are rated 35 amps. IIRC this is the must-blow rating, which, for Lucas fuses, means a must-carry rating of 18 amps. Cylindrical fuses of that sort have at least two age-related failure modes, so it's a good idea to replace all of them every 20 years or so. |
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Harkes Member
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Hi Mark, thanks so much for your clear explanation. My 3rd fuse was rated 30A which should have been 35A as i understood. I think indeed it is a good idea to replace all three after all these years. You guessed right: i don't have the stereo manufacturer's recommendation re. the fuse. But it is 4 x 25 Watt = 100 Watt. So your example of 120 Watt is fine with a efficiency of 50%. Since i think i will turn the volume up occasionally i will stick with your 120 Watt example. This translates to 20A must carry which is close to the JH 18A must carry or 35A must blow. looks like i'm going to need 4 of those 35A fuses i'm getting close and ready for MOT!! thanks a million Mark erik |
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edward_davis Member 
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Has anyone ever done a story for the club journal about refurbishing the PDWA? Mine is on the fritz, and having it disconnected hung me out to dry when the M/C finally gave up the ghost. I'd like to take it apart before I put in my new M/C and clean out the insides, install new o-rings if such things are necessary, etc. Also, should I use teflon plumber's tape on the threads of brake line fittings? If not, is there a proper sealant to use, or do I just put them together dry? Thanks, Edward |
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Mark Rosenbaum Member
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See the old archives, specifically: http://www.jensenhealey.com/msgboard.mv?parm_func=showmsg+parm_msgnum=1008604 The offer of a couple of free EP o-rings made in another post is still active. (Edited to correct errors). Last edited on 12-21-2006 02:06 am by Mark Rosenbaum |
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Jay Member 
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My brake warning light is now on, after I replaced my master cylinder. I bled both the front and rear before I ever had the key on so I'm not sure which half (front or rear) caused the PDWA piston to move. One thing to note is that I first bled the driver’s side front caliper. While bleeding this first caliper pressing on the brake pedal, it seemed to be a bit difficult to get the fluid to flow and I didn’t seem to have any pedal “feel”. At the time I thought that maybe I had a problem with the new MC because it didn’t seem to be returning to it’s at rest position. I then loosened the caliper bleeder a little bit more and got the flow and peddle feel that would be expected. I’m guessing that in the process of trying hard to get more flow at the front caliper (by pressing hard at end of pedal travel); I may have had too much pressure in the rear and caused the switch to set. I read above that the way to reset the PDWA is to loosen either front or rear and press the pedal (trying the front then the rear or the rear then the front). Does anyone know of another way, without the need to loosen any bleeders? If I do loosen a bleeder, should it be “just a little loose” or really open? Which would provide the most direct pressure applied to the PDWA piston, to cause a reset? While on the MC subject, I installed one of those TR250 style units. It seems to fit up just right. The question I have about it is on the fluid reservoir. Almost the entire opening is dedicated to the rear portion of the reservoir. The opening for the front portion is tiny and too small to pour any fluid into it. To get any fluid into the front portion you need to fill the rear portion to what would seem to me to be overfull. It is almost over the edge of the entire opening before it spills over the dam between the two sections. I would think that the dam would not need to be so high. Also the front portion is extremely smaller in volume than the rear portion. More that I would have expected. Any thoughts or comments are most welcome. Thanks. |
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edward_davis Member
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The reservoir is supposed to serve both circuits, so you just have to fill it full to the top. In the original TR application, the MC is angled so that the top of the reservoir is level, and that's why it looks so goofy in the JH. I've only seen one JH with the original MC, out of the ~30 or so that I've seen, so this TR unit must work fine. I haven't had any problems with mine since installation. IIRC, the rear reservoir feeds the front brakes, so it has to be larger to accomodate the greater change in volume as the disc pads wear and the caliper pistons move to accomodate them. The pistons in the drums are much smaller diameter, so they won't need as much fluid when they auto-adjust. And if you have the manual adjust drums, they don't use any fluid, since the adjustment is made on the other side from the pistons. That's why the reservoirs are so different in size, I think. To get the PDWA to shut off, you have to have one person release the bleeder while another applies firm pressure to the pedal. When the light goes off, the pedal pusher must shout to the bleeder operator to close the screw, lest the switch go too far and illuminate the bulb again. In an ideal world, the PDWA would have a built-in return spring, so it would only go off while there was currently a pressure differential. Not so: it simply records that there was a difference. By opening the bleeder screw and applying pressure, you're trying to shuttle the little switch back to the middle, null, setting. I rebuilt my PDWA, you know, and it immediately started leaking out the electrical connector at the top. So I did like Mark suggested so long ago, and I plugged it up with an appropriate bolt. Now it doesn't leak and the light doesn't go off, either. Eventually I'm going to do like Judson (I think?) suggested, and get the inside of the thing plugged up, so fluid can't leak across in the event of a failure. I might even make all new stainless brake lines and get rid of the PDWA entirely. |
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LambandAndy Member 
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I managed to reset mine by removing the switch and using something like a ball end allen wrench (don't remember exactly) in the indent in the piston, pull it back to center. Andy |
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Jay Member
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Andy, Something like that is what I thought may be worth a try. I was hoping someone may have already tried this. Thanks for the tip. With the switch removed I should be able to see which way the piston needs to move rather than guessing. I'll give that a try. Jay UPDATE: Andy, My PDWA must be different than yours. When I remove the switch, all that is revealed is a small steel ball that now appears to be in the up position to depress the switch plunger. The mechanism to move the ball (a groove or taper in the pistons) is not revealed. It appears that I will need to resort to the bleeding procedure to reset my switch. It is interesting to note that the ground path to the switch plunger is by way of a small spiral spring on the tip of the switch plunger. After tweeking this spring, I find that the tail of the spring needs to be positioned so that it contacts the ID of the threaded switch bore. Upon removal of the switch the spring got a little distorted. I removed the switch, and when it looked like I wouldn't be able to reset the switch by going this route, I screwed the switch back in and reconnected the wire. My warning light was now off! I wondered how the switch could reset itself, but when I investigated futher I realized that it didn't. It just was not getting grounded through the little spring. That is when I deflected the tail of the spring outward so it would contact the bore. To complete the ground circuit the spring needs to contact the housing and the switch plunger nedds to be depressed. I found the following reference from the old board to be helpful. Jay http://www.jensenhealey.com/msgboard.mv?parm_func=showmsg+parm_msgnum=1008604 Last edited on 06-05-2008 02:24 pm by Jay |
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