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We've gotten so many TCS posts that it is getting difficult to search. I'm repeating some of the ideas and experiences I consider useful. Two years ago Aeroguy described preventive maintenance very well. It is below. This was complemented greatly by Anders' discussion about replacing older model throttle bodies. There are quite a few detailed posts about TCS experiences, but Utan Tuk has one of the best. If we all posted on TCS like he did it would be helpful. Well, here it is:
Aeroguy’s TCS Preventive maintenance:
"Clean all connectors and fuses with LPS'1 and then coat with DC-4 grease, unless noted otherwise 1. fuse /relay box -check for corrosion at sockets three fuses and two relays unplug spray LPS-1 and reinstall. 2. Pressure switch on powerpack unit. 3. pump motor, power pack unit 4. pump relay, power pack unit 5. liquid level connector, on reservoir 6. electronic controller, on left firewall by reservoir 7. ETS control motor, on intake manifold. 8. ETS position pot, on gas pedal 9. valve block connectors under controller 10. main valve unit, an abs/tcs dist. unit 11. wheel sensors for security and claeaness.
There are things also like fuses under air bag or in GB but these are usually in very good shape. Bottom line is, anything that can collect moisture or splash and develop corrosion then these should be the primary suspect. If water is found drain and blow dry, clean and pack with DC-4 The position/control pot, throttle drive on the drive by wire side sometimes can be a problem but recommend all other areas be attacked first THEN if not corrected this may be cleaned. Hope this helps. "
Re: It was failed to mention that if all else fails and one is
Posted by aero guy (more from aero guy) on Sat, 9 Jun 2001 00:32:32
In Reply to: Aero Guy's TCS Preventive Maintenance List:, Dan L, Fri, 8 Jun 2001 22:21:18
still having TCs problems as such: Starting car all SID checks extinguish but then about 5 minutes later the TCS SID light comes on there is a good chance the ECU controller may need to be recalibrated. (if you have performed the preventative maintenance) For some reason the calibration drifts in the ETS/TCS units and they occasionally need to be cleansed and the software recalibrated. This requires a visit to Saab. Seems to start happening after five or six years or after the interior of the car has had several extremely hot cycles. This also seems more of a problem on the 92 models for some reason. Just thought I'd mention this as a posibility and for what it is worth I have never seen one of these units fail to recalibrate, just lose calibration. If someone checks and states your unit is defective have him recalibrate it first, then check again. Bet it shows good and your problem goes away.
Anders on throttle bodies:
Anders TCS notes, advising to consider replacing old throttle bodies
“Unhook the black connector on the side of throttle body, look at the pins. The middle 5 pins (I said 4 erronously in some earlier posts) should be gold colored. If not, check the partnumber on the black side cover of throttle body.
If the part number is 9109075, you have the old throttle body still, and they don't use gold connectors.
If the partnumber is 9170705, it's the new TB and you should have the gold connectors.
Anders on TCS bleeder valve:
“When the car/engine is piping hot, measure the resistance over the two pins on bleeder valve. It should be around 35 Ohm (nominell value when new and cold is 30 Ohm).
If you have readings over 50 and 60 Ohm and up, the valve is bad.
You can only check when hot, when car is cooled down the value on a bad valve is back down to 30 Ohm.
The best and only way is to drive the car until really hot, or place the valve in a hot enviroment. Next you measure the resitance over the two pins when the valve is still hot. It should be around 30 Ohm.
If it is above 45-50 Ohm, it start to go bad. If the reading is around the hundreds or more, the valve is bad.
The coil inside the valve goes bad with rising heat. When a bad valve is cold, the reading is back to around 30 Ohm. “
Good post by Utan Tuk
“Of course, it happened when my wife was driving. She said "The car would buck and stall, but always restarted, but as soon as I tried to go it would stall again"
What I found: Car starts up fine and all warning/test lights go out. Press slowly on gas pedal - no problem. Press (or release) pedal quickly and she stalls - but the TCS light comes on a second before stall.
Two problems - 1) car goes into LHM and 2) Car stalls in LHM
I check and clean all connections - no change - so I need to fix problem 2 at the scene to drive it home. I adjust the LHM cable so she doesn't stall. Restart, all is normal. Press gas pedal quickly and the TCS light comes on, she goes into LHM and idles.
After reading many of the TCS postings here it seems to me that it must be the Accelerator Pedal Sensor because it only happens with abrupt movement of the pedal and it happens whether the car is stationary (in neutral) or moving in any gear.
I take the car to an independent that has the Tech2 machine to read the codes. The car has four codes - one is "Permanent" (E7590) and three are "Intermittent" (77594, 25251 and 25721)
They replace the Bleeder Valve ($86) and the Bypass Valve ($55), recalibrate and road test. TCS light comes on and she goes into LHM. Pull the codes again, and they’re the same four. They replace the Pedal Sensor ($170), recalibrate and road test. All OK. Those parts, three hours labor, five gold terminal ends - $508.50
When I get home I check the codes in the Saab 9000 M1992 2:5 Traction Control System book and they are as follows:
E7590 – Safety System Activated – 1. If other fault codes occur at the same time, deal with those first. 2. Clear the fault code and test drive the car to see if the fault code is regenerated. 3 Connect a vacuum gauge…
77594 – ECU fault: safety switch 31 – If another fault code exists which begins with a 2, 3, 4, or a 5 (2XXXX, 3XXXX, 4XXXX, 5XXXX) investigate that fault first. Clear the fault code and test-drive the car to see if the fault code is regenerated. If so, try a known good ECU.
25251 – Pedal potentiometer signal faulty or missing – Test resistance values. If resistance values are incorrect replace the pedal potentiometer.
25721 - Pedal potentiometer safety-switch signal faulty or missing – Before starting the test procedure, check that movement of the pedal is not hampered, for instance, by the floor mat. Test resistance values. If resistance values are incorrect replace the pedal potentiometer
It’s quite clear that the two problem generated the two important code – that is 25251 caused the car to go into LHM and 25721 caused it to stall in LHM - and the other codes did not regenerate after the pedal pot was replaced.
So I asked them why they changed the Bleeder and Bypass valves even though the procedures in the book didn't say to do so and they replied “They’re the cheapest parts and they usually fix the problem.”
They also noted that the “Throttle Housing looks original, may need in future”
I hope this can help someone!! If you need the Pedal Potentiometer resistance tests and don’t have the TCS book (but everyone with TCS should have the book!!), drop me an e-mail and I’ll give you the details from mine – just remember it’s the book for model year 1992! gksimms@earthlink.net “
posted by 168.20.196...
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