Saab 900: Found another couple of loose nuts behind the wheel

"Urambo Tauro" (urambotauro) 01/22/2018 at 12:00 • Filed to: saab 900, project, wrenching

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So the Saab decided that it didn’t want to start. Again. Turns out it was operator error, dating all the way back to our first encounter with the car...

Having to replace the ignition gears turned out to be beneficial, because it gave us an excuse to take the shifter housing apart and learn how the reverse lockout mechanism works. The gear selector rod (coming from the transmission) has a tail that extends rearward, beyond the shift lever, where it can interact with the ignition gears. Because of this interlock, the key cannot be removed unless the transmission is in neutral. And the shifter cannot be moved out of reverse unless the key is used to unlock it. Kinda neat, but I can also see why some owners might go out of their way to disable this feature.

But there was another feature that caught my brother and I by surprise. No sooner had we reassembled the ignition switch assembly with its new gears, than it developed a new failure mode: no crank . It was JUST working a minute ago with the homemade hotwire box, but now, nothing. What gives?

With the key in the LOCK position, the shifter locked. In the OFF position, it unlocked the shifter. And ON woke up all the accessories. But the key barrel would not rotate past ON to activate the starter. Something was physically blocking the key from turning to ST.

I don’t know why “G” stands for OFF and “K” stands for ON. Something Swede?

Did my brother assemble the gears incorrectly? Was there something wrong with the contact switch that kept the gears from turning to START? Welp, out came the shifter assembly, for the umpteenth time.

We played around with it on the bench for a while, until I suddenly discovered that the key actually WAS going into a spring-loaded position that felt like START. But it would only do so once. After releasing the key, it could not be turned back to START. Not unless I switched the key all the way off and back on again. This must be some kind of lockout, presumably to prevent starter engagement while the engine is running.

Funny how this diagram lists “Lock - Park - Run - Start”, while the console reads “LOCK - OFF - ON - ST”.

The contact switch houses the spring mechanism, and I’ve got a hunch that the lockout is probably in there too. We were able to confirm that in the spring-loaded position, the switch was indeed connecting the 30 (12V) terminal to the 50 (starter) terminal. So... it works. All we had to do was reinstall the shifter assembly back into the car and pay closer attention to the key positions. We must have somehow tripped the lockout while installing it earlier, and never thought to try turning it all the way off again.

Looking back on it now, I wonder if we actually broke that gear when we were trying to start it on ether, back at Ron’s place. I bet that’s what happened. It was working, and then *snap* it wasn’t. Sixty dollar lesson, right there.

Y’know, this reminds me of the other wild goose chase we went on a few months ago, trying to figure out why the fuel pump received no power with the ignition switch ON. Unlike the domestic vehicles I’m used to, which would prime the pump when the key was turned on, this Saab actually needed confirmation that the engine was turning in order to power the pump. We wasted a bunch of time tracing power and trying to access the fuel pump relays.

Are these common features among European cars? Or is it just a “born from jets” thing? All I know is that we’ll have to be careful to keep open minds as we move forward, and be careful not to make more ASSumptions.

OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars > Urambo Tauro 01/22/2018 at 12:22

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At lest you know there is guaranteed to always be one loose nut right behind the wheel.

IE the person that drives such a wonderful machine. 

MINIGTI > Urambo Tauro 01/23/2018 at 00:18

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My 85 Jaguar also locks out start until you turn it to off again. And I think it does something similar with the fuel pump. It runs of some flavor of Bosch jettronic, I think also similar to your SAAB .

Urambo Tauro > MINIGTI 01/23/2018 at 00:37

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Neat. So maybe those are fairly common things after all, just not for the USDM stuff that I’m used to. Good to know.

MINIGTI > Urambo Tauro 01/23/2018 at 00:52

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It was new to me too. Could be an 80s European thing.

The 86 Camry we had when I was little had an odd thing where you had to press a button on top of the steering column to be able to turn the key all the way to lock.

MINIGTI > MINIGTI 01/23/2018 at 01:00

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Also before that my dad drove this blue 4-door Saab 99: