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I purchased a 2004 Saab 9-5 Aero (113K miles) in August (love it) and drove it for a couple of months with no issues. It died while driving about a month ago and would not restart, so I had it towed home. After some research and being a DIY guy, I purchased a Tech 2 clone and spent a few weeks researching "crank, no-start" issues and trying a few things to resolve the problem. I ohm'd the crank position sensor and it is within spec (890 ohms). The fuel pump relay activates and the pump makes noise (I don't have a fuel pressure gauge kit to confirm the actual pressure). I don't know how how to test the direct injection cassette, but there were no misfires prior to the car dying. Finally, the Tech 2 arrived and, after configuring secure access, I checked for trouble codes. The only DTCs displayed are for the Airbag system, which consist of the following:

B100 Front Collision Sensor Left, open circuit or short to ground/B+
B77 Drivers Side Airbag Sensor, open circuit or short to ground/B+
B78 Passenger Side Airbag Sensor, open circuit or short to ground/B+
B96 Passenger Seat Belt Sensor circuit, open circuit or short to ground/B+
B29 Passenger Side Deployment, Resistance too high

IDK how to proceed at this point. The car has never been in an accident and I was driving it when it died (and no airbags were/are deployed). Would these trouble codes cause a crank, no start condition? Is this indicating there is a problem with the airbag control module? Any advice on how to proceed from here would be greatly appreciated. Thanks in advance.
 

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Since you have a Tech II, you can attach it, go to "Read Values/Activate" for T7, and observe real-time if the ECU thinks the engine is cranking.

Couple of notes:
  1. Get a battery charger, charge up the battery fully, and keep the charger on while doing your tests
  2. Tech II/ODB II readers seem to lag a while before registering RPMs, so you might have to crank for five or ten seconds--don't crank for too long, though, it's not good for the starter
None of those SRS codes will cause a no-start.
 

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Easiest is to pull the DIC, check to see if it is OEM and swap it with another one (borrow one from somebody) and check if that is your issue.
.
 

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Hi EdT, Thank you for the info. I have a charger and have kept the battery fully charged (even while testing). I'm still learning how to use the Tech II and the process has been less intuitive than I originally hoped it would be. I attempted to "Read Values/Activate" as you suggested and, while cranking, my Tech II reboots. It is being powered from the OBD port. Do I need to connect the Tech II to external power to prevent this problem from happening? Also, which sensors should be monitored to determine if the ECU thinks the engine is cranking? Thanks again for the help.
 

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Hi Bob, Unfortunately I don't know anyone else with a DIC, so swapping it is not an option. However, I'm think about ordering a new OEM unit and trying the swap that way and, if it's not the problem, keeping it on hand for when the installed unit eventually fails. Is there a way to test the current unit other than swapping? Can you provide a recommendation for the best place online to purchase an OEM unit (not an aftermarket)? Thanks again for your help.
 

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Yes, sounds like your clone Tech II needs an external power source while cranking.

Top thing in "read values" for T7 should be RPM, so there's the place to start.

Agreed that Tech II is not intuitive. You can look up the meanings of the various readings in WIS. However, WIS does not necessarily provide a full explanation of the more esoteric ones.
 

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most probably external power source will not help as Tech always uses the one in the OBD port if it is available. You would have to pin out the power supply in the OBD port.
 

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Hi Bob, Unfortunately I don't know anyone else with a DIC, so swapping it is not an option. However, I'm think about ordering a new OEM unit and trying the swap that way and, if it's not the problem, keeping it on hand for when the installed unit eventually fails. Is there a way to test the current unit other than swapping?
Sorry but I can't help you on shopping for a DIC, I haven't bought one for many years.

Where are you located?

There plenty of Saab shops or euro affiliated shops around that love to help.
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most probably external power source will not help as Tech always uses the one in the OBD port if it is available. You would have to pin out the power supply in the OBD port.
Shouldn't it switch over quickly enough if the power on the ODB port is interrupted?

The Tech II that I have access to is a Vetronix, so I haven't really encountered this problem.

ETA, my ODB II reader, which doesn't have an internal power source, doesn't reboot if I try to start the car, though the car starts too quickly for the reader to tell me the cranking RPM.
 

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TECH2 uses external power when connected.
You should read RPM when cranking, you should see about 200 RPM (this is lowest RPM which enables ignition and fuel to engine).
 

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I'm north of Houston
Are any of these near you?



 

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Shouldn't it switch over quickly enough if the power on the ODB port is interrupted?

The Tech II that I have access to is a Vetronix, so I haven't really encountered this problem.

ETA, my ODB II reader, which doesn't have an internal power source, doesn't reboot if I try to start the car, though the car starts too quickly for the reader to tell me the cranking RPM.


Sure, that works because you're taking power away from the OBDII port and then the DC jack fills in. But if you have both plugged in and crank the engine, the Tech 2 will restart. It's well documented, well discussed. I observed what you observed which is why I thought the converter on the DC jack would work, but I found out what others did... if there's power on the OBDII port, the tech 2 disregards the dc jack. You can get around that by removing the 12v from the OBDII connector, but I didn't want to mess with every car I needed to use the tech 2 on.

Here is one of many threads on the topic:

https://gmtnation.com/forums/threads/fix-tech-2-reboots-if-engine-started.16563/
TECH2 uses external power when connected.
You should read RPM when cranking, you should see about 200 RPM (this is lowest RPM which enables ignition and fuel to engine).
I have an engine starter speed of 160 rpm and engine still starts, so no need for 200 rpm.

The only thing that should be testet if engine speed is available, it doesn´t matter if it is 120 or 200.
 

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I hesitate to say this: since its respectable to diagnose before swapping any parts, but I have read and heard o folks having CPS failures even with good OHM spec readings... though recalling and a quick search of CPS testing on this site, suggests that its good spec testing CPS that fails when hot situation, rather than a cold start. But worth noting....just in case you want to give something a try and are getting restless with the classic tech 2 shut down at start situation and a roadblock to the diagnostics effort. :)

good luck
 
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