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TCM issues ?

5K views 5 replies 4 participants last post by  turbojohnny 
#1 ·
ive looked all over for help .hopefully someone with some knowledge can help. 1st i have a 200 saab vert. i think my TCM may be going bad? does a used one have to be married to my car? every now and then. more lately my check car will kinda jerk. my check engine light comes on. then the tranny light. with my car then losing gauges, turbo, ac. later it will run fine after turning off for awhile. worse during warm weather. any suggestions? or even if i cld be pointed in the right direction would help. was pulling p1923/p1908/p0455 ... just replaced dic n plugs.
 
#2 · (Edited)
P0455 = Evaporative Emission System Leak Detected (large leak)
P1923 = No BUS data from TCM(Transmission Control Module)
P1908 = No BUS data from MIU (Main Instrument Unit)
These are the code meanings I have.
PO455 is the least of the worries. It could be something as simple as a faulty seal on your fuel cap. Or a split pipe or a pipe off it's fitting.
I'm assuming you have a 2000 (year) 93 petrol automatic. If this is correct, My interpretation of the faults, as an untrained mechanic is as follows.
The TCM receives info from various sensors and sends it to your dashboard and the MIU.

Speed sensor
Trans fluid temp sensor
Neutral position switch .......... All communicate with the TCM
Kick down switch

The TCM communicates with...........The MIU & The Dashboard display
I would be looking at checking the condition of the switches/sensors, wiring, plugs and plug connections. Including the TCM & MIU connections first. There is a good diagram to look at, at "jimellissaabparts.com"
Hope this helps
Cheers for now
Dave
 
#3 ·
Sorry for the late reply.. A gazillion repairs done on my Saab since April.. Anyhow problem is not fixed.. The hotter the weather is ..the worse the problem. Now the temp is 100- 110F my car will go into limp and throw codes 1908 1923 1701 within 5 minutes of driving. Today it died actually while driving and even though no overheating. I had to let the car 'cool' down for 15 min . before I could drive it the other 5 miles home.. Why would tcm.. Ecu..or mui cause this in hot weather .. When it was in the 80s I could at least drive for 30 min before this happened.. All symptoms gone if car sits for an hour or so.. And the temp outside has cooled..maybe take to a damn shop this week.. I'm confused what to replace and where to start..thinking tcm.. Then ecu..then mui... Thermostat......
 
#5 ·
So after all this time, I still have the saab . Replace the TCM. No more going into limp mode. But I still get the abs and brake light on. So I'm thinking I may also need another oil pressure sensor. A transmission pressure sensor. Possibly a Speedo or and sensor. Saab equals spend $.
 
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