I just replaced the motor in a 1999 Yukon.

Tiny
BACK YARD MECHANIC 469
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  • 1999 GMC YUKON
  • 12,500 MILES
I just replaced the motor in a 1999 yukon denalie, it has a rebuilt transmission with only 500 miles on it it worked fine when I pulled the engine but now I have no 3rd or 4th gear , I don't have the scanner to set the timeing (perfectly) but the truck runs like new , I read in a haynes manual that the transmision sencors work with the engine sencors, since I am getting a camshaft sencor code could that be why it won't shift into 3rd or th?
Wednesday, December 5th, 2012 AT 8:07 PM

10 Replies

Tiny
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The ignition timing is not adjustable. What you messed up with the distributor is the injector and secondary ignition synch with the reference signal. That's why you have a cam code. I suspect it's actually a correlation code. As far as the transmission, just look around for something left unplugged.
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Wednesday, December 5th, 2012 AT 8:24 PM
Tiny
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Ok then why does it tell me in the haynes manual that the distribtor must be turned with a scanner attatched to be within +or - 2 degrees? I call that timeing I had a correlation code and the engine would backfire untill I found the propper spot by turning the distributor then they went away now my can obd2 diagnstic scanner gives me a p0340 camshaft position sensor A circuit (bank 1 or single sensor code, I have went over the veicle with a fine tooth comb and nothing is left unplugged, the doner engine came from a bone yard but I used the intake, distributor, waterpump ect from the truck because it was in better shape it has all new caskets top to bottom new plugs cap rotor the whole 9 yards but no 3rd or 4th gear what I need to now is if the sync between the engine and transmision sencors could be causeing this since the book says they work in synk I didnt remove he transmision when I changed out the motor but I made shue everything was plugged in anyway i'm baffled, fluid levle is good in th trany wat ese could this be?
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Wednesday, December 5th, 2012 AT 9:08 PM
Tiny
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Oh and te correlation code was caused because I had the didtributor off a tooth sory orgot about that , all in ll engine runs like new and tranny had all gears untill after te engine swap
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Wednesday, December 5th, 2012 AT 9:12 PM
Tiny
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[quote]ok then why does it tell me in the haynes manual that the distribtor must be turned with a scanner attatched to be within +or - 2 degrees? I call that timeing[/quote]

You would be wrong. The timing is determined by the crank sensor. Turning the distributor synchs the injector pulse and secondary ignition with the primary signal and yes you do have to use a scan tool to set that and it has to be withing 2 degrees of zero or it will set a correlation code.
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Wednesday, December 5th, 2012 AT 9:16 PM
Tiny
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You can also burn the piston or a valve if that is off from burning too lean.
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Wednesday, December 5th, 2012 AT 9:18 PM
Tiny
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Ok I undestand all that but were does the whole deal with the engine and transmision sensors working togeather and will that cause it to not shift into 3rd and 4th gear? This is driveing e nts I know te transmission was fine when I started the job and I can rent the scanner to get the timeing right on from my local parts store f noting is unplugged why does 1st and 2nd gear work fine but no 3rd or 4th? Do the sensers from the engine controle that as well?
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Wednesday, December 5th, 2012 AT 9:42 PM
Tiny
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The only sensor that would have anything to do with transmission shifting would be the TPS and I suspect that truck may be equipped with drive by wire so that's unlikely.
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Wednesday, December 5th, 2012 AT 9:47 PM
Tiny
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Also the dono engie came from a van, wat are the chances of the flywheels being differant could the issue be caused from a wrong flywheel? I sed te flywheel from the van cince they seemed t be identical
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Wednesday, December 5th, 2012 AT 9:48 PM
Tiny
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I see i'm stumped it was all good till the engine swap, no bad wires or anything unpluged i'v been woring on cars ince I was old enogh to turn a wrench, about 25 years now and i'm about to pull my hair out
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Wednesday, December 5th, 2012 AT 9:52 PM
Tiny
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I have no idea what you may have done during the installation. The first step would be to use a professional scan tool on the factory side and see if there are any codes and monitor the solenoids on the data list.
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Wednesday, December 5th, 2012 AT 10:36 PM

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