Nope, the ABS system relay is a regular Bosch that tests good and is wired up in accordance with the wiring diagram. So my search continues.
Nope, the ABS system relay is a regular Bosch that tests good and is wired up in accordance with the wiring diagram. So my search continues.
Are you on the FB c900 group? I don't do FB but I know the admin, who reports it's a good group, pretty active, constructive.
In reply to procainestart :
I'm on *a* 900 group, but I'm not sure if it's *the* 900 group :) Good thinking, though - I'll poke around there.
I was taking a deeper look at the wiring diagram and noticed that the pump relay is actually a little bit different than a regular relay.
Pump relay:
Regular relay:
The pump relay has a path with diodes around the coil. I don't know enough to be able to understand what the difference is, but it's definitely a difference.
That is a flyback diode. It's there to protect ciruitry from the voltage spike created when the arm in the relay moves back from it's powered position to it's resting position.
Beyond that, it should have no effect on operation.
Did a little more prodding around today and might do some more later. So that I don't lose my notes, here's what I found:
- ABS ECU probably not causing it. Unplugging the computer does not change the behaviour.
- Relay, while weird, is probably not the cause either.
- Disconnecting the brake pressure switch results in the brake fluid light not coming on, so its path to ground is open without the pressure switch itself.
- The fluid level float sensor appears to be working. There is continuity between pins 1 and 2 and it is open between 3 and 4. That should be the right reading for a full reservoir.
- Pulling the pump relay out, with the ignition in "drive" (that is, +30 closed to +15, +X, and +54), there is no voltage present on pin 85.
- Disconnecting +15, but leaving +X and +54 closed to +30 (the "halfway position" on the ignition switch), there is voltage present on pin 85.
- There is a 3-pin connector near the hydraulic unit that appears to be #57 on the wiring diagram. The wires coming from the central harness seem like they've been a bit melted at some point. That connector feeds the ABS ECU from +15 on pin 27 with a trip to a diode that I don't understand from one wire and the 10amp fuse in the ABS panel from +54 on the other wire. That fuse goes on to feed both the ABS ECU on pin 2 and pin 86 on the pump relay.
- With #57 disconnected and the pump relay removed, there is still voltage at the 10amp fuse, but it's less than battery voltage. Instead of the 12.6V that I read on the battery, I'm getting around 10 volts. I didn't check with the fuse removed, but that's something else I should check on.
- The wires for the pressure switch have definitely been monkeyed with before. Someone has pulled back the looming and has cut in to the insulation in what I assume was an attempt to check voltages. So I think that the problem with the brake pump not running something that may have caused the car to be parked way back in 2015.
- If I turn the ignition on, I get battery voltage on pin 2 of the pressure switch connector. If I disconnect +15 from the ignition switch, I lose voltage on that pin.
Eastside Tim came over and we tried a few more things.
The pressure switch seems to be testing bad but I'm not quite sure what to make of it. When the pressure is low, it should have continuity between pins 1 and 4 which should ground the relay and turn on the pump but it's open between those.
With the brake fluid level sensor connector removed, the abs ECU unplugged, and the abs and pump relays removed, it does have continuity between pins 1 and 2 on the connector for the pressure switch. The only way I can figure it's getting to ground would be going through the charging system light.
With the abs computer unplugged, we grounded pin 14 on the connector. That's an alternate ground path for the brake pump relay, I assume so the computer can turn it on. Interestingly, when we do that with the ignition in the regular drive position, the pump runs and the brake fluid light comes on. So it seems like it's grounding the light through the pressure switch somehow?
As I was getting ready to leave, I noticed that the fuse box was warm to the touch. I took the lid off and found that the fog light relay was getting hot. I pulled the relay out and took a look at it. Funny story, but I found my brake pump relay! Somehow someone swapped the two relays at some point. So I repinned the socket and put the right relay back in to place. It had absolutely no effect but at least it's right now.
Since the pressure switch doesn't seem to be working correctly, I think I may see about getting a replacement. I'm not sure that's the whole problem, but I'm pressure it's not right.
There are several sources of +12V in the gauge cluster. One is the +15 feed that feeds some of the lights, including the brake system lights, and instruments, one is +54 that feeds more lights, including the charge light, and several are direct to the battery through the fuse box. When I pull the turn signal fuse, which provides power to the charge light, the pump runs when I turn the key to "drive" like it should. The other lights on the dash then come on slowly and dimly.
I think my problem might be in the gauge cluster?
Okay, I went ahead and disconnected the two electrical connectors on the cluster. Now the brake system doesn't work at all. I think that means that the whole thing is grounding through the cluster.
294 is the pressure switch. According to the manual, when it detects 140 bar or lower, it closes terminals 1 and 4 which connects the relay coil to ground. So next up, I need to check and see if I have +12V at terminal 86.... And I do.
Next up I took another look at the brake fluid level switch. That's #299 above. The connector has continuity to ground on pin 3 and pin 4 has continuity to pin 2 on the pressure switch connector (#294), but the level sensor itself is open between terminals 3 & 4.
I went ahead and put a jumper between 3 and 4 in the level switch connector and now when I turn on the key, the brake pump works. It will run until it shuts off and then if I pump the brakes it will run again.
After plugging the gauge cluster back in, though, I now have almost no lights on the cluster. The right turn signal light works and every time it flashes the gauge gauge bounces up. Now I'm thinking that there's a bad ground on the cluster, maybe? Even when I put everything back, though, I still have no gauge cluster, so maybe something got pulled loose when I pulled the connections? Either way, I think the gauge cluster is a part of this mystery somehow.
In reply to wae :
Wait, that's not right. 3 & 4 are supposed to be open on the level switch. So why is grounding that making it work?
Any chance a 1993 900 would have the same cluster? There's one at the Louisville Besslers that has been there less than a month.
In reply to eastsideTim :
Since it's a convertible, yes. That would also have the brake pressure switch that I think is bad. Perhaps I need to work out a trip to Louisville. It looks like Tuesday I could manage to take off work, stop in on the way(ish) at Buffalo Trace and try to score a bottle of something nice, and make my way over there. Let me put that on my list of things to maybe do.
There was a '93 convertible in town on fbmp that was listed as a parts car for $300. Despite doing daily searches for Saab's under $800 I never found it until it was posted on a Saab group. And I was too late. So definitely taking the day off tomorrow and going to Louisville.
wae said:There was a '93 convertible in town on fbmp that was listed as a parts car for $300. Despite doing daily searches for Saab's under $800 I never found it until it was posted on a Saab group. And I was too late. So definitely taking the day off tomorrow and going to Louisville.
If you end up in the Louisville area and don't get what you need from a junkyard, call me or send a message. There are more than a few parts here.
Well, yesterday was a Blanton's day and I didn't feel like cutting in to my junkyard time for EH Taylor, so we went straight to the yard. Given that the pictures of the car showed it with the top retracted, I didn't have much hope that the top would be worth pulling. And it wasn't. So no good there. Since it's basically a giant bathtub, the ABS computer was basically full of water, so I left that behind as well.
On the good news front, however, I was able to score another one of the brake pump relays, the entire brake assembly - pressure switch, reservoir, pump, master cylinder, and accumulator - a driver's side sun visor, and the ignition switch. All for just under $32. I want to go over after dinner tonight and see if we can't swap the pressure switch.
Good tip on the knee bolster, too! We were sitting there staring at it trying to figure out what was holding it on when I remembered that I had been warned about that!
Went over to the shop to swap out the pressure switches and it wound up being far more frustrating than it should be.
Step one was to run out and get a 36mm deep well 12-point socket. That's what The Internet says will take off the pressure switch, if it's deep enough to clear the electrics. The Husky socket I picked up from the Home Despot worked perfectly with the impact gun to zip out the new switch. And that's when things stopped cooperating.
I put the socket on the switch in the car and... it's too big. So I guess I need to go out tomorrow and track down a 35mm. Or maybe a 34mm. I'm assuming that someone replaced the switch at some point and found a batch of pressure switches that were a different size. Between the brake line that they ran over it, the brake pump itself, and the coolant line, I can't get a pipe wrench or a vice-grips in there.
Pressure switch is on and other than the fact that it's now got continuity between pins 1 and 4 like it should, things are still not right. I think that the fact that the parking brake light is always on, even with the brake switch disconnected, is a big clue. There's something about how on start, the supply (presumably to the gauge cluster) from +54 is opened and the cathode of the diode is earthed in order to do a lamp test on every start. So the next thing I'll check will be that supply line at the cluster.
I did however solve a mystery. When we first started going through the car, we found this translucent green plastic ring in the console. Figuring it was a leftover happy meal toy or something, we just set it aside and moved on. When we were taking parts off the one in the junkyard, in the same console was an identical ring. So this has to be an actual part of the car. While looking for pictures of wiring connectors I tripped across a picture that shows that ring going around the lock to provide the illumination for the ignition switch. I guess it's not unusual for folks to forget to put that in when they're taking the center console off!
I'm about to give this thing a Viking funeral.
No voltage drop from the battery terminal to the pin that feeds the charging light, so the ignition switch relay is making good contact. I tried the new ignition switch and it made no difference. I'm pretty much at a complete loss. There is something either grounding where it shouldn't and/or not passing voltage where it should and I lack the skills to be able to find it and I'm kind of getting tired of screwing with it.
I guess my next step is going to go to the 152-series of bulkhead connectors and check each one for any voltage issues.
I know it is a bit hack-ish, but has anyone converted these to vacuum-assisted brakes? A booster and a check valve seems like it would be easier than dealing with this mess. Although, now I am wondering about the feasibility of running my hydro boost setup with an electric pump instead of the power steering pump.
In reply to eastsideTim :
I can't remember if I saw a conversion done on a Saab, but I know I saw someone convert this system to vacuum-boosted brakes so it can be done, but it renders ABS inop. But I don't think my problem is with the brakes any more. The brake pressure switch was definitely bad, but I've got a new one on there now. I think the accumulator needs to be replaced, but that's not going to cause any electrical problems - that just means the brake pump is going to run more frequently. And I've got another accumulator that I can put on. It's actually a pretty cool and compact system. The biggest problem is that some of the parts like the pump relay and the pressure switch are either unobtainium or stupid expensive. A new pressure switch is something like $500.
All that said, though, I don't think that's my problem. With the whole brake pump system unplugged, I've still got berkeleyed up lights on the dash. When I turn the key to "drive", the parking brake light comes on even though the switch is disconnected. With the gauge cluster unplugged, the other end of the trigger wire for the parking brake light at the switch is open, so it's not getting ground from either the convertible top or the parking brake itself. If you ground that connector, the light gets a lot brighter all of a sudden, so that says to me it's pulling its ground from somewhere it shouldn't. After letting the ignition stay in "drive" for a couple seconds, the Check Engine light comes on very dimly and goes back out and then the oil pressure light fades to about 50% brightness and stays on. I don't think the charging light comes on, even though it should. With everything plugged back in (brake fluid level, brake pressure, pump, ABS computer, engine computer, gauge cluster, ignition switch) it operates exactly the same as with all of those things unplugged (ah, actually with the fuel injection ECU unplugged, there's no check engine light), so I think my problem is outside of the brake system. It may have been caused by the brake system, or caused by someone troubleshooting the brake system, or it may have caused the problems with the brake system. No way of telling right now.
So this might be a remove, clean, and reconnect every ground you can find situation?
In reply to eastsideTim :
All the grounds look pretty good. I'm guessing there's a connector somewhere that's corroded or something, so I think I'm going to have to go through and check each wire on each connector.
This has become a test of biblical proportions -- consider naming the car "Job." ;-)
This isn't going to solve the problem, but if the charging light isn't coming on, it could be blown. And it needs to be there for the alternator to self-energize. And it's not the same as the rest of the bulbs in the cluster. A quick search on Saabnet says, the bulb is gonna be blue, 2W. The majority of them are black, 1.2W. The manual says a 1.2W bulb fits, but the alt. may not charge at idle.
That said, the circuit involves 152A, 152B, and 152C connectors, so if the bulb's good, that might suggest, potentially, a connector issue, which, if true, could be a clue to the overall issue??
In reply to procainestart :
First off, that relay is set to go in the mail. Every time I've been heading to the post office with it, something stupid has come up. But since I also have to get my check to the Kentucky Department of Revenue or whatever they call themselves by tomorrow, it's going to make it in the mail for sure!
Tim and I actually had a voyage of discovery about the whole charging bulb being an integral part of the charging system a few years back. I still don't understand the black magic behind it. But I did verify that all the bulbs are good. The cruise bulb was blown out, actually, and I replaced it with one that was only for Europe. The charging light did work at one time, but it's worth checking it to make sure it's still good.
Now that I read that, I wonder if somehow that burned out cruise bulb was part of what was making it work differently.....
I spent a little time this afternoon mapping out the connector and pin for each and every connector that goes to/from the gauge cluster. Next step is to check every one of them.
Been checking the wires on the back of the cluster and haven't found anything yet.
When I turn the key on with the parking brake off, the ABS light is on at normal brightness and the Park Brake and Brake Fluid lights are on dim. The check engine light and oil pressure light fade on dim and when the check engine light goes out the charging light fades on dim. If I ground the parking brake switch, the Park Brake and Brake Fluid lights go to full brightness and the charge light goes out.
I bypassed the ignition system relay because I read that it can fail and cause weird gauge cluster lights. No change.
After testing all of the terminals on the left side, I realized that the park brake was on. I don't know if that means my voltage readings are worthless, but there was no appreciative voltage drop on any of them. The worst one was the rheostat for the cluster lights that had about 133mv drop between the cluster and the battery terminal.
Okay and what the unholy berkeley is this about? I went ahead and started the car. It started up and after I gave it a blip of the throttle, all the lights but the ABS light went out. When I shut the car off and turn it back to drive, I get the same slow fade of the lights on with the parking brake light on no matter what. But once the car is running, the parking brake light behaves the way it should.
Is this a bad alternator?
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