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2003 cts
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Discussion Starter · #1 ·
Hey all, I'm new to the group though I've read posts for some time. My problem is the tranny in my '03 CTS. The last two times I drove it every shift (up & down) was extremely hard, jerking the car. Check engine light came on and the codes are P0700 (transmission control system), P1779 (engine torque delivered to tcm signal) & P1795 (can bus throttle body position). Any insight would be appreciated before I take it to the dealer. Thanks.
 

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The Throttle Body electrical connection may need to be cleaned.

Try this.

Buy a can of Electrical Cleaner [spray] at your local auto parts store. With the engine turned off, disconnect the Throttle Body electrical module/connector and spray both male and female connections well. Make sure m/fm modules are dry and re-connect. Disconnect and re-connect again. Do this procress a few times just to make sure the m/fm prongs make good contact.

After re-connecting the electrical module to the Throttle Body, turn key to On position. Reset the ECM by using the F1-F6 radio feature. Turn-on engine and take the car for a spin.

Let us know if the tranny issue cleared-up.
 

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2003 cts
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Discussion Starter · #3 ·
Thanks, I'll give it a try this weekend. Hope it clears up the problem! Can you tell me where the Throttle BOdy module is located?
 

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2003 CTS sport/lux
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14 Posts
CT Essence, good post, that worked for me so far (knock on wood), just the other day i had all the same symptoms that were listed, & KOT referred me to this post. Thanx
 

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Good to hear, CeCeySay.

I am totally convinced that most auto tranny [hard-shifting] issues are directly related to poor module prong connectivity at the [TPS] electrical connection or a Throttle Position Sensor (TPS) that needs to be taken off the throttle body for a cleaning.
 

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2003 cts
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Discussion Starter · #7 ·
Just got back from a test ride and no problems, even under hard acceleration! Great advice CT Essence; thanks! When I entered the ECM found 17 codes; gonna take me a while to sort them all out.
 

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O.G. CTS Sport/Lux, V Grilles/Bumpers, sittin on 20's
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273 Posts
Thanks CT ESSENCE you the man! Same problem I had, works great now. Thank you!
 

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O.G. CTS Sport/Lux, V Grilles/Bumpers, sittin on 20's
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So it seems I may have spoken a bit too soon, tried this fix on Friday, worked great all weekend, made a trip out of town to go snowboarding yesterday on the way back to problem started again, hard shifting, especially down shifting in lower gears, but not nearly as bad as on thursday and friday when the problem occured originally. I should also mention that this all started on thursday when my electrical seemed to have shut down when driving out of no where, restarted the car and my shifting was off??

Think I should try cleaning the module again?
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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6,414 Posts
Paco...does all of your electrical work? things like the radio and all that good stuff. i had very similar symptoms with the hard shifting and some of the same codes on my CTS, turns out i had a blown audio fuse under the back seat drivers side and it fixed my problem. i thought it was weird that an audion fuse would cause this, but after looking at schematics, that particular fuse went through the DIC and HVAC unit, and also sent signals to my TCM, which caused the hard shifting and other CEL codes
 

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O.G. CTS Sport/Lux, V Grilles/Bumpers, sittin on 20's
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Ya it all works fine, it was just that one time last week that all my gages dropped and my power steering went off, and the battery light came on. Resarted it and it was ok, but on the way home the shifting was all off and even the traction control light would come on and I could barely accelerate until I restarted it again. Since I clean the TB Electric Module its been much better, but has started again slightly since yesterday...
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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6,414 Posts
if i was in your shoes, i would go through each and every fuse and verify they are good. i doubt this will actually fix it, but it is a piece of mind knowing they are good. also, have you ever SeaFoamed your car? this may be something you want to consider doing as well, cause if you have a clogged throttle body or fuel system, i can see this being an issue
 

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O.G. CTS Sport/Lux, V Grilles/Bumpers, sittin on 20's
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Cool, I'll try cleaning it again, and if it persists I'm gonna go get the codes read from my guy as the check engine came back yesterday and I don't have a DIC...

Thanks for the responses guys I really don't know what I'd do without this forum lol
 

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2003 CTS "Ebony Maria" 2005 Cadillac STS "Grace"
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he has an aftermarket head unit in there and no longer has the DIC
 
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