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97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)

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97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)

  #1  
Old 10-15-2013, 12:21 PM
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Default 97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)

About 4 months ago my check engine light came on showing a few trans related codes (Ill post the history below) I saved the codes then cleared it as the vehicle ran fine and was shifting correctly. After that had no issues until about a month later when 3 codes popped up again all trans related. This process went on until about yesterday when I noticed that it seemed like my trans was stuck in 3rd, I.e. it struggled to accelerate and didn't want to downshift at all. Here's the sequence of codes popping up:
Code:
Sometime July/Early August
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P0785 - SHIFT/TIMING SOLENOID
	P1860 - POWERTRAIN (SAID MULTIPLE DESCRIPTIONS)
August 22nd
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P0753 - SHIFT SOLENOID A ELECTRICAL
	P1860 - POWERTRAIN (SAID MULTIPLE DESCRIPTIONS)
September 19th
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P1860 - POWERTRAIN (SAID MULTIPLE DESCRIPTIONS)
October 14th  1
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
October 14th  2
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P0753 - SHIFT SOLENOID A ELECTRICAL
	P0758 - SHIFT SOLENOID B ELECTRICAL
October 14th  3
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P0753 - SHIFT SOLENOID A ELECTRICAL
	P0758 - SHIFT SOLENOID B ELECTRICAL
	P0785 - SHIFT/TIMING SOLENOID
	P1860 - POWERTRAIN (SAID MULTIPLE DESCRIPTIONS)
October 14th  4
	P0740 - TORQUE CONVERTER CLUTCH CIRCUIT
	P0753 - SHIFT SOLENOID A ELECTRICAL
	P0758 - SHIFT SOLENOID B ELECTRICAL
On the 14th the problem really started to repeat itself as you can see above. The odd thing was that between the one of the occurrences on the 14th I cleared the codes, shut the vehicle off, restarted it and then it ran fine with no issues or codes popping up until I shut it off a restarted it again.

My thoughts are leaning toward the ignition switch at this point just because of the variability of everything. However to this point I haven't done much diagnostics on the vehicle besides comparing to other similar problems posted on the forums. What would be the sequence I should follow before throwing parts (and my $) at this?

The general sense I got from searching seems to be that I will check the trans fuse (#24 15A I believe?), if thats not blow then check the trans connector solenoid power wire, then next step would be to check the individual solenoids I believe after dropping the pan.

Now with that being said the vehicle does have some history I should note. December of 2011 I replaced the ignition switch as It was causing the engine to shut of at random intervals (normally when coming to a stop). Summer of 2012 I did a bunch of maintenance work just to catch everything up as I had no history of the vehicle before I got it (which was november 2011). That work mostly include fluid changes including the trans and filter, which i had a heck of a time as I struggled getting the crossbar off so I just worked around it.

Basically all this leaves me with is the thought that it's the ignition switch again (Which could be likely as I had to use a generic brand and not AcDelco like i would have liked because I was in a bind to get back to school). And if it's not that switch maybe I bumped something in the trans and its just slowly been creeping up on me. If anyone could shed some insight on their experiences or let me know if I'm moving in the right direction it would be greatly appreciated.
 
  #2  
Old 10-17-2013, 01:06 PM
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you can try changing the ignition switch. for whatever reason they ran a ton of stuff through that switch. i too was having a similar problem and i kinda traced it to the signals not being sent to the solenoids from the computer but thats about as far as i got. also usually when my trans would be stuck in 2nd it would blow the ign/gau fuse
 
  #3  
Old 10-17-2013, 04:04 PM
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Got some time today to start testing a few things. First thing I tried was the #24 trans fuse, tested it with a light no power in any position. Next on my list was to test the clstr fuse but I can't for the life of me find the fuses under the hood. If I remember correctly they are supposed to be drivers side but I don't see anything. I've attached pictures and maybe someone can point me in the right direction. On a side note would it be worth my crawling under and checking the transmission connecter seeing as it nots even getting power at the fuse?

Also yesterday the key tumbler wouldn't release my key or turn into acc position, I've read similar stories about that being connected with this problem. Is there any way in the mean time I can get it to unlock?
 
Attached Thumbnails 97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)-2013-10-17-15.51.42.jpg   97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)-2013-10-17-15.53.05.jpg   97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)-2013-10-17-15.53.13.jpg   97 Blazer Multiple Trans Codes (P0740, P0753, P0758, P0785, P1860)-2013-10-17-15.53.22.jpg  

Last edited by Jeklund; 10-17-2013 at 04:06 PM.
  #4  
Old 10-17-2013, 04:39 PM
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After some digging around and looking at diagrams from what i gather the trans fuse (#24) runs right from the ignition switch and that switch is the initial source of power for that fuse and all the related transmission stuff. Could someone clarify this for me?

If thats correct my problem lies with the ignition switch again and I'll go ahead and order one.
 
  #5  
Old 10-18-2013, 01:41 PM
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i messed with mine like 4 years ago so youre really jogging my memory when i barely know what i did yesterday. i had a bunch of links bookmarked but that computer blew up. said what wire did what at the trans connector and i was able to find out which wire wasnt being sent power and just made my own source and that fixed the problem.

but this was all on a older 93 truck. also i kept finding people say its the ignition switch. there was all sorts of stuff tied into it, stupid stuff like the rear defrost. so if like the rear defroster was bad it would keep blowing the fuse causing your trans to start in 2nd.
 
  #6  
Old 10-18-2013, 03:10 PM
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I found the diagram in another thread I believe its pin E (the pink wire). If there isn't power at the fuse wouldn't it make sense that there wouldn't be power at the connecter on the trans as a result?
 
  #7  
Old 10-19-2013, 05:39 PM
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Just another update, found out the key issue was just, what seemed, unrelated to this issue. I just had to wiggle the key abit to get it to move the cylinder. Also I went out to the vehicle today and drove it around the block and it was shifting fine again and no codes popped up, as well fuse #24 had power.

Based on the fact that I know the switch is getting power (as if it wasn't a whole load of other things wouldn't be working) and that when I do get power at fuse #24 the tranny shifts just fine (which would infer that the connection from their to the trans is working right), i feel like its safe to assume its the switch that's causing all these issues again. I've gone ahead and ordered a new AcDelco switch and it should arrive late next weekish. So for the time being I'm going to hook up my light to the tranny fuse and observe over the next week to see if when the tranny goes into limp mode it correlates with the light going out at that fuse thus confirming that its switch.

If anyone has some insight to share it would be greatly appreciated as I'm kind of just winging this and going off of I gather from the forums and my testing. I'm definitely no expert, especially when it comes to wiring so any ideas/thoughts/suggestion are definitely welcome.
 
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Old 10-29-2013, 02:51 PM
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Just wanted to update my situation, Last night I installed the new ignition switch and went for a little drive. No codes popped up and as of today still nothing has so it appears that was the issue.

Only thing left to do is fully put the dash back together, however I seem to have less screws than when I started so that should be fun... If anyone has a suggestion on where I could pick some random ones up it would be appreciated as I'd hate to make a trip to the wrecker for a couple screws.
 
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Old 03-28-2015, 04:59 PM
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I know this thread is a little dated, but I am wondering if you completely solved the problems you were having with the new ignition switch, or if they all started coming back after a few days?
 
  #10  
Old 02-13-2018, 04:27 PM
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HELP ANYONE was the ignition switch the fix???
 
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