wildwagonz Posted February 3, 2010 Share Posted February 3, 2010 Hi all, I just finished changing the engine in my friends 02 Legacy (threw a rod at only 114k miles) No problems tranny wise prior to the engine swap, got the engine in last night and now I have a flashing AT Oil Temp light and a Check Engine light on as well. I read the CEL with my code reader and it comes up P0748 pressure solenoid circuit. Then I did the "secret handshake" to get the TCM codes and I get 7 long flashes and 5 short flashes for a code 75. I have searched all day today online and came up with the possibility of dented transmission pan when i jacked it up to drop the new motor in. I checked the pan and it doesn't appear bent but the bottom does seem a slight bit (VERY SLIGHT) caved in. Its just the ever slight concaved, and when I say slight i is barely noticeable. Could it be thats the problem? I am going to pull the pan off tomorrow to check everything out. Just was wondering if someone can elaborate on what exactly happens with the solenoid or if someone else has had this happen to them? Could it be something else? I checked all the connectors on the transmission on the top near the firewall and they all are fine. Thanks for your help in advance. ~Tim Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 3, 2010 Share Posted February 3, 2010 The codes you got indicate that the line pressure duty solenoid circuit either has an open circuit or a short. It might be external, although it doesn't take much denting of the pan to cause problems. As a point of reference, those solenoids usually measure just a few ohms (about three). Recheck the trans connectors, making sure that there are no bent pins and that they fully engage. Verify that no wires have gotten pinched. One other thing to check is the dropping resistor that's usually mounted to the right (passenger) strut tower -- make sure it didn't get damaged or disconnected. Quote Link to comment Share on other sites More sharing options...
wildwagonz Posted February 4, 2010 Author Share Posted February 4, 2010 I have checked the wires none were crushed and I never thought about the resistor. Would it possibly go bad on a motor swap I thought those usually never go bad. Are the clearances between the tranny pan and the solenoids that close? All was completely fine before the engine swap. Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 4, 2010 Share Posted February 4, 2010 (edited) If you've got an ohmmeter available, disconnect B11 from T4, and check the resistance from T4/pin#5 to ground. It should be around 3 ohms (+/- about an ohm). If much higher, there's an open in the solenoid circuit, if lower, a short to ground. Edited February 4, 2010 by OB99W Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 4, 2010 Share Posted February 4, 2010 I have checked the wires none were crushed and I never thought about the resistor. Would it possibly go bad on a motor swap I thought those usually never go bad. The dropping resistor isn't delicate, but since it's in the engine bay there's a chance of damage to it or its wiring during an engine swap. They also sometimes accidentally get disconnected while things are being prepared for pulling the engine. Are the clearances between the tranny pan and the solenoids that close? All was completely fine before the engine swap.When jacked, the trans pan can deflect enough to hit, then spring back somewhat so that it looks like there wasn't enough movement to cause a problem. Quote Link to comment Share on other sites More sharing options...
wildwagonz Posted February 4, 2010 Author Share Posted February 4, 2010 OK......so I measured the resistors ohms and it came up 12.7 figured it was within spec. Then checked the tranny connectors they were not crushed all seemed fine. Measured ohms on #5 red wire to ground got nothing, pulled tranny pan measured solenoid pin to ground still got nothing all other solenoids were measuring something around 12 ohms but nothing on the line pressure solenoid. So does that mean its bad? Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 4, 2010 Share Posted February 4, 2010 [...] Measured ohms on #5 red wire to ground got nothing, pulled tranny pan measured solenoid pin to ground still got nothing all other solenoids were measuring something around 12 ohms but nothing on the line pressure solenoid. So does that mean its bad? No continuity through the solenoid coil would certainly indicate a problem. Quote Link to comment Share on other sites More sharing options...
nipper Posted February 4, 2010 Share Posted February 4, 2010 Sometimes thats the best way to measure things by comparison. Yes it has an open (which is bad). nipper Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 4, 2010 Share Posted February 4, 2010 Naturally, an open (high/infinite resistance) reading is bad. However, comparison only goes so far -- while most of the solenoids should measure around 12-13 ohms, the line pressure and 2-4 brake solenoids should be around 3 ohms. If either of those measured 12 ohms, they'd be bad. Quote Link to comment Share on other sites More sharing options...
wildwagonz Posted February 5, 2010 Author Share Posted February 5, 2010 Well im thinking solenoid but before I go dropping 180 bucks for a non returnable one at the dealer, does anyone here have access to a used one possibly from a junk tranny lying around? Quote Link to comment Share on other sites More sharing options...
wildwagonz Posted February 12, 2010 Author Share Posted February 12, 2010 Fixed..... New Solenoid Fixed the problem, Thanks for the help! 1 Quote Link to comment Share on other sites More sharing options...
OB99W Posted February 12, 2010 Share Posted February 12, 2010 Fixed..... New Solenoid Fixed the problem, Thanks for the help! You're welcome. Congrats! Quote Link to comment Share on other sites More sharing options...
akouma Posted October 9, 2010 Share Posted October 9, 2010 i have the same problem so should i get the LINE PRESSURE SOLENOID to get the problem fixed Quote Link to comment Share on other sites More sharing options...
tirod Posted February 12, 2014 Share Posted February 12, 2014 Post #20. http://forums.nasioc.com/forums/showthread.php?t=1297696 Have the same problem, new-to-me used trans. Code, flashing AT light, hard shift to second, no overdrive. Of course I used a trans jack, they all pretty much lift using the pan. The issue is that a dimple in the pan holding a magnet is directly under the solenoid. Use of a jack at that point pressing upward will contact it as the dimple eliminates most of the clearance. It's vulnerable. Jacking the pan and distorting it won't likely cause it to starve the filter pickup. It's located on the valve body 2-3 inches above the pan and would be obvious if crushed that far. But that dimple is deliberately placed where it is. A better pan would be solenoid friendly. I haven't seen one designed to create damage. Bears consideration. Replacing the solenoid does not guarantee a repair. The wiring, dropping resistor, and TCM are suspect until proven innocent. Quote Link to comment Share on other sites More sharing options...
Timbum36 Posted September 6, 2016 Share Posted September 6, 2016 Put a motor in my 03 legacy had the same problem same code replaced the line pressure selnoid and it also fixed my problem had a small dent in pan as well thank a lot guys you have been a big help Quote Link to comment Share on other sites More sharing options...
Dexstar Posted December 4, 2018 Share Posted December 4, 2018 Also having the same problem after a motor swap.....Hmm seems to be a trend here? Occam's Razor?? I'm trying to reverse myself thru all these threads to extrapolate the troubleshooting info I desire. not sure if I've overlooked it or just haven't found it yet. Can somebody help me with the nominal values and or procedure for testing the dropping resistor? Thanks! Quote Link to comment Share on other sites More sharing options...
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