SaabCentral Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
3,421 Posts
Discussion Starter #1
I completed all the wiring for the new towbar I fitted to my 2.1 sedan, tested it all with my trailer connected (worked), had it disconnected and a few minutes later the car just stopped running. No warning. Perfect idle to dead stop. Cranking won't get it to re-start.

Done a big of diagnosis today. CEL comes on when ignition turned on, then goes off like normal. Do not get CEL when cranking and it doesn't light up when I stop trying to crank. No tach bounce when cranking (but never really noticed that previously anyway). Battery is good, fuel (and pump) both good. Motor won't run with fuel pump manually jumpered on.

Decided to get codes out of the ECU - 12231 and 12254. I've seen reference in searches to 12254 not being in Bentley's table (I checked and it's not). There is a 12251 code listed that means 'no signal from TPS'. Being LH 2.4.2 it's the potentiometer-style of TPS which I don't have a spare for (guess it's time to source one).

I'm going to commence a full diagnosis of the EZK ignition system when I have the time so I can determine if the crank sensor might have pooped itself. I know I've done this sequence once before on my black 2.1 hatchback and I remember the fun I had with replacing it's crank sensor.

There's a big body of experience in this forum of 2.1 owners so could anyone suggest some things to look out for? Unfortunately I do not have a 2.0 turbo motor's distributor (with hall sensor) to try and use as a 'dirty substitute' for the 'empty sensor' distributor as a quick test for a dud crank sensor.

Craig.
 

·
Registered
Joined
·
3,421 Posts
Discussion Starter #3 (Edited)
Thanks yes quite a few people are pointing the finger at the CPS. BTW does anyone know if code 12254 from the ECU is mis-printed in Bentley as 12251? I'm aware that without the crank signal coming from the EZK unit to the ECU it won't enable the fuel pump, so when I had the fuel pump manually jumpered yesterday and still no-go that's telling me it's ignition.

got a couple of days off work coming up. sounds like I have a job in front of the RHS inner driver replacement now. ;-) Given that the crank pulley has to come off to get the sensor mounting out, it'd be a good time to try and renew the oil seal as well (any tips on doing that without a special tool?).
 

·
Registered
Joined
·
3,421 Posts
Discussion Starter #4
I've done part of the Bentley manual's ezk testing. Coil primary resistance is a bit high and I couldn't verify with certainty that the ignition amp switching function is correct. The knock sensor was fine. Next up if the weather warms up enough will be CPS testing.
 

·
Registered
Joined
·
3,421 Posts
Discussion Starter #5
Done the rest of the testing today.

Checked coil again and it's good. Both primary and second resistances in spec.

I think I have a dead ignition amp as the 'switching function' measurement at the coil shows only about .35 volt with both my -124 Bosch modules (spare plus original in car) but I get success with a -139 Bosch module. Voltage rises to 6 v then drops to 0 after a cpl of seconds like book specifies. Are -124's and -139's interchangeable? The -139's actually use pin 7 for something but the -124's don't.

I don't get a pulse from control unit to amp module when cranking with starter. Couldn't work out what was going on there.

With the hall sensor test I'm getting a constant 5.015 volts as I slowly turn engine using flywheel and screwdriver in teeth as a lever - turned it a whole rotation and no variation in sensor output. The hall sensor power test is good. Just under 12 V showing up

So I think the hall sensor has failed (thereby disabling the ignition) but also suspect the ignition module too.

Thanks to Bill @ Saabits I have a kit here already to deal with the hall sensor. It seems there are aftermarket replacements for the Bosch ignition amp modules - new oldstock ones are probably unobtainium.
 

·
Registered
Joined
·
5,543 Posts
I think you cannot swap the modules. I don't know that pin 7 is the secret sauce, but on turbos the ICM controls dwell, and on non-turbos the ICM does not and EZK does. Thus it's important to use the correct module. I posted a thread about this recently... I can't remember when or in what context, but within the last few months.
 

·
Registered
Joined
·
5,543 Posts
Here you go...

 

·
Registered
Joined
·
3,421 Posts
Discussion Starter #8 (Edited)
Thanks I figured there was a difference since -139 was showing up for turbo's and -124 for non-turbo's. Magically I've found an Australian seller stocking new Bosch -124's.

As I now know the CPS is dud, and in a very difficult to access spot, it's time to go 'deep diving'. BTW this is my cut-down 27 mm socket that I've used once before to take off crank pulley on another 2.1 car:

https://flic.kr/p/2jf4hec
The access is very limited and I've never what the genuine Saab SST might be to do the same job.

Craig.
 
1 - 8 of 8 Posts
Top