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guyslp

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guyslp last won the day on January 6 2019

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  • Car Model and Year
    Sedan de Ville - 1989
  • Engine
    4.5L OHV V8

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    Staunton, VA
  • Interests
    Cadillac and Rolls-Royce cars, orchid growing, parrots

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  1. Hello All, My question is not directly Cadillac related, as the need is arising with my 1996 Buick Roadmaster Estate Wagon, but it could certainly crop up on various Cadillac models too. The upper dashboard surface in this car is vast and after 19 years it's beginning to "disintegrate" for lack of a better word. The slightly glossy (and I do mean slightly) finish it had is gone and the surface is now turning to dust which is clearly of the material the dash is made of. It is not cracking at all, just getting "dull and dusty." I'm really not looking to achieve a "like new" result but the car has sentimental value and I'd like to arrest the decay and keep any more from happening if possible. Has anyone tried anything that they like which will halt the disintegration of this sort of plastic material and keep further damage from occurring (or at least slowing it down signifcantly)? I'm trying to avoid anything that would result in a very glossy finish once applied. The surface area of the dash in this car is vast and in the past (long past) when things like ArmorAll were applied you simply couldn't stand the resulting glare while driving. Any assistance is most appreciated. Brian
  2. Jim, I can see why lowering the car might be important from several perspectives once the key is off and the car is suddenly unladen. But as for elevating the car after it's off, I simply presumed that would take place when you start the car again. Were you able to tell from the wiring diagram whether the system is supposed to be "perpetually on" for both the raising & lowering functions? The way I read it was that it should be fully on only when the key is in the "Run" position and that the exhaust function to allow the car to lower is perpetually active (or at least it is if you have a functioning battery). Am I incorrect? Brian
  3. The leveling light does work. It is the top center light on the right hand information center panel. Here is a PDF scan of the ELC Wiring Diagram from the Service Information Manual. It should print out in readable size on 8.5x11" paper. That should help give some clarity, at least to those who can read these things a bit better than I can. I have not tried running the rear defogger, which is on fuse 7. Brian
  4. Next part of the saga. . . Have manually tested the exhaust solenoid as far as activating it goes. This uses the Bk/LtP and Bk/DkP wires which go directly to the solenoid which peaks out of the top of the compressor. Since I have no residual pressure to vent I have no idea whether it's actually working as it should or not, but the distinct click when power is applied and the corresponding dull thunk to the touch when the power is removed is clearly felt. One thing is that the exhaust solenoid does not, if the Service Information Manual is accurate, cycle on for anything other than when weight is removed from the car and the car was previously raised to compensate for it. The two pertinent passages from the SIM: Air Replenishment Cycle The air replenishment cycle operates as follows: Height sensor position is checked when the ignition is turned on. If the height sensor indicates it is not necessary to raise or lower the car, an internal timer circuit is activated. After 40 seconds the compressor is turned on for 4 seconds. This ensures that the air adjustable struts are filled with the proper residual pressure. If weight is added to or removed from the car during the 40 second delay, the air replenishment cycle will be overridden and the car will raise or lower after the normal delay. [which is noted elsewhere as 7-10 seconds]. Lowering the Car When an excess load is removed from the rear of the vehicle, the body is forced upward, causing the height sensor arm to rotate down. The downward movement of the arm causes the internal timing circuit to activate. After an initial predetermined time delay of 7-10 seconds, the sensor grounds pin 2 which completes the exhaust solenoid circuit to ground. With the exhaust solenoid energized, air starts exhausting out of the struts back through the air dryer and exhaust solenoid valve into the atmosphere. [There is a small outlet pipe that's barbed right next to the solenoid on the compressor housing, and I presume this is the actual exit point for exhausted air.] As the vehicle body lowers, the height sensor arm is rotated to its original position. When the vehicle body reaches its original height (+/- 1"), the sensor opens the exhaust solenoid circuit which prevents air from escaping. A minimum air pressure of 48-97 kPa (7-14 PSI) is maintained in the struts by the air dryer valve. This residual pressure provides improved ride characteristics when the vehicle is carrying a minimum load. Here is a diagram of the pins on a Bosch-type relay and the Hella relays in the car are of precisely this type. They have a resistor across the coil pins - 85 and 86, but that won't be relevant to the diagnostic information that follows: The only logical way this relay could operate is as a switch where, when the coil is energized based on a signal from the height sensor, the compressor is turned on. This means that the normally open pin, 87, would be switched such that the +12V common source pin, 30, now complete a circuit. Now for the "Oh, %@$*&^, how did I miss that!!" part: The fuse was missing for the ELC system!! I did check this at the start (see the third post in this thread), but the fuse block is "upside down and backwards" as far as reading it and I misinterpreted either the 20A fuse directly above or below slot 12 as being in slot 12. I thought that slot was a "not used" (for what reason I do not know upon reviewing the fuse block information). Once the fuse was back in place the compressor fires up without issue. However, I don't think the saga is over. The compressor is firing up when the car is not running and the key is not in the ignition. I know the exhaust solenoid is wired such that it can be activated at any time in case you park, unload a bunch of stuff, and the level has to be lowered. Nothing I've found so far suggests the compressor is supposed to be able to run when the car is off. I have not allowed the thing to continue running for the full 2.5 minutes where it's supposed to shut off when the system has a major leak, as mine does. I intend to leave the fuse out until I install the new shocks with functional air bladders. Also, a big thanks to rockfangd for the information about the ELC test connector. I decided to pull the battery and dig around the area after I found an illustration showing where it should have been. Somehow, at some point, someone managed to wedge the connector on the end of that yellow wire under the battery tray, making the whole thing invisible until the battery was out. The connector is exactly the same as the green one on white wire shown in one of my pictures earlier in the thread that emerges from the loom with the wiring for the three relays on the strut tower. Upon further research, this is the fuel pump priming test connector. The Service Information Manual makes reference to a "Car is Leveling" light that's located at the top center location on the right side information center panel and it is, as noted by Kevin, green. It illuminates when the compressor comes on. I just put the fuse back in after the car's been sitting for about 30 minutes and has no key in the ignition - it fires up after a delay of approximately 40 seconds. The car was not used much by the previous owners, and I presume they got tired of hearing the compressor run for the long periods it will run when the system has a major leak. Brian
  5. Kevin, Thanks for that bit of info. I still can't find that light in the car although it could be on one of the information centers. Like I said, several other GM owners of Buicks that share this system said they definitely don't exist on their cars of the same era. A few more photos: Height Sensor View 1 Height Sensor View 2 Mystery Connector w Lt Blue Dust "Accordion" View into Mystery Connector I just wanted people to see the height sensor and environs. The pop-on connection to the trailing arm is removed because I had it off at the time I was taking the photos. While digging around in the front loom in the area behind the compressor I found a dedicated wire-wrapping tube coming out of the loom with the above pictured connector on the end. I doubt that this has anything to do with the ELC and, based on the degree of crud that was on the connector before photos, I doubt it was ever connected to anything. I can't see a place anywhere that this would have inserted in to and have chalked it up to "option not present" since I know that looms are made such that they can be put into every car on the assembly line no matter how they're optioned out. If anyone recognizes it, or what it's for, I'd be curious to know. Brian
  6. Partial report back: The compressor is located on the front left side of the car, in the engine bay, just in front of the left strut tower that has the 3 relays attached to it. There is no "Car is Leveling" light on my car that I can find. I was told these were deleted before 1989 (probably because a yellow light coming on/going off struck people as a warning rather than informational). This light is documented in the Owner's Manual, but is not shown on any of the information centers. I guess it could be there, but if it is it has never illuminated. I can find no yellow wire anywhere near to the compressor. The only wire that I could find was taped to the loom and emerges from the same spot that the relay wires do. It is white with an odd green connector that does not look like a standard male or female slide connector. You can see it taped in place in the first two pictures that follow and I freed it up to do close-ups. The connector from the to the compressor that plugs in to the loom has four wires: Black (Bk) [this wire is heavier gauge than either with the purple tracers] Black w/Light Purple tracer (Bk/LtP) Black w/Green tracer (Bk/G) [same heavier weight as Bk wire] Black w/Dark Purple tracer (Bk/DkP) The loom wires that correspond to the wires above are: Bk -> Bk White (W) -> Bk/LtP Green (G) -> Bk/G Orange (O) -> Bk/DkP These are shown in the pictures as well, but I have close ups of the compressor connector but not the loom connector. The difference between the light purple and dark purple tracers does not read at all well in the pictures, but it's clearly different to the eye. Compressor and environs Compressor Close-Up Odd Green Connector w/White Wire from Side Odd Green Connector - Close-Up Connector-to-Loom Connector #1 Connector-to-Loom Connector #2 More will follow as I get to working along the electrical circuits from the height sensor to the compressor. Brain
  7. I have a homemade power supply cable that has jumper cable type clips on one end and micro alligator clips on the other with a fuse and an on-off switch in between. This is connected directly to the battery terminals. In this case, I'm supplying power using this cable directly to the two wires in the 4-wire connector that goes to the ELC compressor that are for the compressor itself. The two thicker wires, which are black with green tracer and solid black, are the two. The positive goes to the black w/green tracer and negative to the black wire. The only ELC relay I've found documented is the one in the relay center and that's hard to get to quickly and easily when working in the engine bay. It's shown on the scan of the relay center label that I found on the car itself that I posted a few posts back. I suppose I could pop out the glove box and jumper the correct slides on the ELC relay socket to see if it runs from there. I could also keep a finger on the ELC relay to see if it's being activated at any point, which it should be just for the "keeping the residual pressure consistent" cycling. I'll have to look at where, precisely, the exhaust valve is located and whether it ever clicks. I will need my partner to assist with key turns for that bit. Brian
  8. OK, here's the next part of the saga. I managed to get the rear of the car up on ramps today so that I would have easy access to the height control sensor arm. Upon popping off the connector to the loom I found the pins on the sensor and the slides in the socket to be spotlessly clean, looking like new in fact. I gave both sides a shot of Caig DeOxIt for good measure and put it back together. Tried manipulating the sensor arm per the service manual to get the compressor to cycle on or exhaust and no dice. Nothing made it come on after any waiting period. I did, however, manually apply power to the compressor and it runs like a champ. Here's the link to a video I made [in mp4 format | in AVI format] during that process and leak testing with soapy water. There is the slightest leak where the line to the shocks attaches to the overpressure prevention valve, but nothing of any significance, particularly given the push-on connector setup. I want to make clear that the video makes it seem as though the compressor is extremely noisy, but it's not. When you get the camera and microphone this close to capture video the audio is exaggerated. The bladders on the shocks that are on the car are completely shot, so even if I've got great pressure to fill them they're never going to rise. I couldn't get to the connectors to the shocks themselves with the car up on ramps; I'm not that limber. I do intend to get the car up on a lift so I can get at the connector on the shock to see if I've got air pressure making it all the way back to the shocks. Still, though, the crux of this problem is that the compressor is not being cycled on by the car itself. Does anyone know if any of the three relays that are mounted on the strut tower just above the compressor are related to the ELC system? You can see these in the video when I pull back a bit. Since I've already eliminated the relay in the relay center as being the issue, I'm down to only several other possible options: 1. Something is defective with the height sensor and the whole system will not operate without it being intact. 2. There is another "secret relay" or other electrical switch, etc., between the height sensor and the ELC relay, or the ELC relay and the compressor. 3. I've got some other electrical fault somewhere prior to the compressor. Any ideas of what I should be looking at next? Also, does anyone know of an on-car or bench testing technique for the height sensor that doesn't depend on the compressor coming on? I'd like to know if it's possible that there's a fault in the height sensor, but have no idea how I'd go about that with things in the state that they're in. If, in the end, I can't get the ELC working is there a way that I could rig the compressor to a switch so that I could manually adjust the shocks as necessary? Finally, people have asked me to pull codes, and I did. The only code I'm getting is an E52 [PCM Memory Reset]. Brian
  9. I will have to check codes again, but I've read elsewhere that this system was not monitored by OBD until much later when OBD-II came along. I did find that this car does have some sort of diagnostic connection port below the knee roll on the driver's side, but it's definitely not an OBD-II port and I have no OBD-I equipment. The only codes I know how to get are through the key-press sequences that display them on the climate-control panel (or I think that's where they come up, it's been a while since I last queried for codes). My guess is that I'm going to have to put the new struts on the car (including front ones, which are not part of the ELC system) and then continue my troubleshooting. If I can get the new struts (which I have manually inflated and deflated off the car, per the manufacturer's instructions before installation) to inflate by manually running the ELC compressor, but they instantly deflate afterward, then I know I've got an issue with the exhaust solenoid. If they don't, and the thing still won't run on its own I will have a whole new can of worms. Brian
  10. I really try to be as specific as possible about what I have (and have not) yet explored when dealing with any problem. The only time I'm not is when a post is an initial "help, I'm lost here!!" type. That's one of the reasons I always request that those who've "been there, done that" please share and make a point of posting specific things I find that most certainly are not out there in online or print documentation I have at my disposal. There was definitely a major change to the relay center that must have taken place even before the 1989 models (or many of them, anyway) ever left the assembly line. When I opened up that 1991 car and found exactly what was in mine, plugged into the exact same sockets in the relay center, I knew something had to have changed. My car was not changed to conventional rear struts and it appears that those that are on the car may well be original. The ELC system parts are all there and I've already tested that the compressor not only runs, but produces a very generous and forceful air stream. I'm going to have to get the car back up on a lift to have easy access to the height sensor arm and to do some exploration in that area. If it is "dead" then I know it will be more than a bit of a pain to get a replacement. If anyone knows how to bench test these things so I would know if things are "switching correctly" with the sensor off the car then please let me know how one goes about that. I'm still at a loss as to why the compressor isn't cycling on at startup just to keep the static air pressure at the correct level. I know that it wouldn't succeed given that the struts on the car have dry-rotted bladders but I'd think it would cycle on to make the effort. Brian
  11. Now for the latest twist. When I was about to start putting the glovebox back in I decided to poke my head in much closer to the gaping hole in the dash to see how things might be photographed. What did I spy but a Relay Center layout sticker, sticking in a place where you'd never see it unless you took off the underside of the dash. I have taken the liberty of adding annotation text for each of the icons used, but other than that it's a straight scan of the sticker. Sorry the image is not inline, but the forums software doesn't allow the link format that Google Drive uses as something you can directly embed. It's clear that there was a major rearrangement of the relay center that was done after the Owner's Manual and the Service Information Manual were both produced. I wonder if this was corrected for the 1990 and later model years? I am still not getting the compressor kicking on when I turn the key to the start position, even after waiting. If something's not wrong with the height sensor then I really don't know where to look next. Brian
  12. Well, things get curioser and curiouser . . . I popped out the glovebox and behind it one could clearly see the relay center. However, there were only 7 out of the 10 relays, with the missing ones being A, B, & K on the relay center diagram. Relay K is what's noted as the ELC relay. So, off to the local salvage yard I go to scrounge some relays. When I got to the 1991 Sedan de Ville that was there that did not appear to have ever had the dash touched I popped out the glove box and what did I find: exactly what I found in my car!! I did grab the relays out of the car since it never hurts to have some spares around but when I got home and tried to put one in at position K it turns out that the relay center is not set up to take a 5-pin changeover relay there and upon closer inspection the three slides it does have in that position do not correspond to any sort of relay I've ever seen. Positions A & B appear to be specific to cars with the Bose stereo system since you can tell there are no female slides inside the sockets for those two positions. The horn relay in position J is definitely the horn relay. Both the 1989 Owner's Manual and the Service Information Manual show position K (the top rightmost as the thing is oriented in the car) as being for the ELC relay, but by all appearances this was changed before the production run ever began for these cars. If anyone knows if one of the other relay positions is actually for the ELC, or if the ELC relay was either deleted or moved, please share. If anyone happens to have a 1989 De Ville that they could check and/or photograph the Relay Center for me I would really appreciate it. I can tell you that removing the glovebox is an incredibly simple procedure. Once you've removed the screws, three across the bottom front, one facing you at the upper left corner, and the two that hide along the top front edge the entire glovebox lifts out, door and all. You don't even have to remove the connectors for the light or trunk release, you can simply tilt the whole glovebox aside. While I've got mine out I need to take documentary photos, too. Brian
  13. Unfortunately, the pump does not cycle on at when the car is started. Yet it works just fine when manually powered. This system doesn't seem to be all that complicated, but I can't really find any documented explanation for this behavior other than "bad compressor," which is clearly not the case. But, your comment does make me suspect the relay now more than the height sensor since the thing never powers on at all. Brian
  14. Yes, you read correctly. I wanted people to know that I knew I needed to do this (and now have) but hadn't done so yet. FYI, the car under discussion is a 1989 Sedan de Ville and there are no fuse blocks in the trunk anywhere. There's one "pure" fuse block that's located on the driver's side under the steering wheel area and the relay center that's behind the glove box lining contains a few fuses as well. Here are scans from the Owner's Manual for each. As I suspected, the 20 Amp fuse in slot 12 appears to be in perfect shape. At this point that makes the next two most likely culprits either a faulty ELC height sensor or a bad ELC relay. I suspect the height sensor more than I suspect the relay. The Service Information Manual describes the ELC height sensor as "a solid-state device which controls the functions of the compressor and exhaust solenoid." Given that description, I don't know whether there would be anything I could possibly service other than making sure that the connector to the electrical harness isn't "crudded up" and that the height sensor operational check outlined in the manual goes as documented. If anyone has "been there, done that" and has any tips, please share. Brian
  15. I've been working on the car and now have replacement front strut assemblies and rear Gabriel air shocks. I did not want to install these until I knew that the ELC compressor was working. Today I applied a 12V source to the compressor leads and the compressor works like a champ. The existing shocks have dry rotted air bladders, so they don't inflate at all. However, my issue is that the compressor does not come on at all, even after the 7-second waiting period after starting the car is over, when the trunk is heavily laden and the car is clearly low in the back. What is the next best thing to check in the diagnostic sequence? I haven't yet checked fuses, but will. I don't know how often relays go on these cars and don't want to take out the glovebox lining next if I can avoid that. I have seen the ELC control switch arm that is attached to the rear suspension. My gut tells me that this would be the next most likely culprit given its location and exposure to road crud. If anyone has experience with trying to determine why a functioning ELC compressor isn't being triggered to run by the car, please share. Thanks, Brian
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