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2002 gmc envoy_slt
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3 Posts
Discussion Starter · #1 ·
I am going crazy! I wan to start by saying thank you for all of your help so far. I have been referring to this site with problems I have had for a month now and have answered every question I have had. Now I have an issue that I can't find. I have a 2002 gmc envoy that blew an engine. I replaced it with a 2005 engine(might be a 2006 engine). I swapped all sensors and fuel rail/injectors. Tried to start and nothing. No crank everything else worked.I used the 2002 PCM. So then I used the 2005 PCM. Fired right up. Now my issue. The indicator will not go into park. The transmission goes in but will not read. Won't work with either PCM. All grounds are on. Replaced neutral safety switch. Tried switch manually and still nothing. Replaced ignition switch just for the h*** of it. Worked before engine swap. Envoy runs and drives great. When I park it I lose power to the interior. Locks, dash, radio, everything stops working but will stay running. When I turn the car off the lights flash every so often for no reason. Battery goes dead after a few hours:mad: Have run out of patience with it. Can't afford to just replace parts. Someone please help!! Thanks in advance
 

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2003 chevy trailblazer_lt
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50 Posts
In regards to the battery draining, you have a parasitic drain somewhere. You could test the various circuits with a multimeter to determine with ones are drawing large amounts of current while the car is off (although it is normal for certain circuits to draw current), or you could unplug fuses to see if the battery still drains to determine which circuit is responsible.

For the shifting issue, did you check the shift cable that goes from the gear selector to the transmission. There are many reports of failing grommets that cause similar issues.
 

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2002 gmc envoy_slt
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3 Posts
Discussion Starter · #3 ·
Thanks for the reply. Yes there is a drain causing the battery to go dead. I think that it is due to indicator on the dash not completely going into park. The PCM still thinks the vehicle is in gear. The shift cable is fine. The transmission mechanically shifts perfectly and goes through every gear. The indicator on the dash reads every gear except to park. Checked fuses and grounds. Still confused
 

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2002 gmc envoy_slt
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3 Posts
Discussion Starter · #5 ·
Today Ihave tried everything and still no park. Have tried three neutral safety switches, checked harness on switch, tried three different pcms, changed bcm. Totally stumped. Took to two mechanic friends. Hooked up to snapon modis scanner. When not in park everything works fine. Then shift to park I loose power to the bcm and everything in the vehicle. Scanner reads communication error. Would the instrument cluster cause problems like these? Are the computers routed through the cluster? HELP!!
 
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