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I’m new to the forum as of today but have subscribed to Eric’s videos for a while now, I’m losing my sanity over an OBDII P1765 code, I will try to make this short. My car is a 1997 Lexus ES300 with 178k, I’ve had a P0773 code solid for over a year. So, I finally purchased the SL lock up solenoid to replace the old one and get rid of the P0773 code because emissions testing is coming in December. All seemed to go smoothly when I dropped the valve body out of the transmission, the old Lock up solenoid was clearly bad after testing both its resistance and putting voltage to it (no clicking). I put everything back together seemingly perfect, turned on the car and the code P0773 was gone, but in its place were the codes P0753 & P0758 which meant that now there was a problem with the electrical circuits on both shift solenoids 1 & 2! Apparently in my haste and difficulty putting the valve body back into the transmission, I severed the two power wires to these two shift solenoids. So, this being my first time soldering wires and I did the best I possibly could and heat shrinked the both of them, reassembled and started the car again. Both previous codes were now gone but in their place I now have code P1765 which points to an electrical malfunction in the linear accumulator valve solenoid which is the last of 4 solenoids in the valve body that I didn’t damage the wiring to! Once again, I drop the transmission pan to find both power and ground wires to the linear solenoid cut and partially severed. So, I soldered and heat shrinked these wires and put it all back together and I still have the code P1765. Obviously these wires have become so brittle and weak over the last 17 years of soaking in scorching transmission fluid and maybe I am a little clumsy but shouldn’t the solder job I did on this last circuit work? I tested this circuit for resistance every step of the way putting it back together and it was between 5-5.5 ohms. The car shifts hard, clunks from N to D with much hesitation and feels like I’m starting off in 2nd gear even accelerating from a full stop. I’ve tried clearing the code and it wont even turn off the light for 1 second. I’ve even tested the circuit from the wire harness plug that goes into the top of the transmission since its all put back together and the resistance seems fine. When the ignition is in the on position but not running, the ECM is sending a continuous 2.4 volts to this circuit but when I connect the harness back up to the plug and solenoids with the car running, I back probed the current and its super low around 200- 350 milli-Volts. I’ve ordered a new wire harness from Lexus which will be here in a couple more days along with a new Linear Solenoid but my biggest worry is that the ECM could have been damaged when this circuit was severed and maybe grounded out on metal. Could the wires to this circuit be compromised but still show normal resistance? I tried putting voltage to the solenoid side and sparks flew which indicates a short to ground still and the solenoid clicked. Any ideas from anyone that has experience with soldering transmission solenoids & sensors would be greatly appreciated! Eric, if your reading this? PS: I’m not inexperienced in Automotive repair and diagnostics but in all honesty, this is the first time I’ve ever played with internal transmission parts/ solenoids.
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You’re on the right track with the replacement of the harness. This issue is not just with your car, many (including our own VW) have severe issues with the harnesses in the transmissions. Oh everything is fine–until it gets disturbed. Then it’s major headaches with the insulation on the wiring cracking and falling apart.
As for the ECM getting damaged? It’s possible, but most computers have overload protection circuits built in just in case something does short out. With a bit of luck, the ECM should be fine. Just keep the fingers crossed.
S-
Thanks for your reply Tedybear315, I appreciate your input on my problem! Yes, I’ve also realized, this being my first valve body drop, that transmission wires and connectors are very weak and fragile. Its good to know you don’t think its the ECM, I’m one of those guys that researches codes/problems on the internet before I just go taking something apart and others have run into code P1765 with the conclusion of the ECM being bad. I will have the new harness in on Tuesday along with a new linear solenoid valve, but I’m going to disassemble to transmission valve body today. This time I will be working from both the bottom and top and I’m going to completely remove the wiring harness from the transmission so we will see what gives. The only thing I’m not sure about is testing the linear valve solenoid because it operates on up to 5 volts but I have no way of limiting the current in my jumper wires from the battery to the solenoid (12 volts). Do you think that putting 12 volts to this solenoid for just a second is ok or could this potentially damage the solenoid? Should I go to Radio shack and try to build a makeshift variable voltage supply tester? lol I wish I had the power probe Hook at a time like this.
I personally would not jump a 5vdc device with 12vdc. (and my primary job currently is a electronic/repair tech for a video arcade company. I do mechanics work for my family now, as I left the industry a while ago.)
How about finding a cheap 5-6VDC power DC pack from a local store like Radio Shack and using that for testing? The inexpensive ones are low current, so a momentary test shouldn’t damage things that are not already on the way out.
Best of luck with it!
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I haven’t visited radio shack in a while, I’m not familiar with the power pack you are speaking of, could you include a link for me if at all possible? Yeah, I’m not too hot on the idea of putting that much voltage on this linear solenoid either because it of what it does/how it operates and sends signals back to the ECM. A product link would be greatly appreciated! Thanks again for all the help, I’m about to go outside and start putting my Lexus on jack stands, not looking forward to it.
http://www.radioshack.com/product/index.jsp?productId=15365586
It’s a selectable supply. 1amp so it’s a bit of a wimp. Then again you do not want a lot of amperage, just enough to see what works and doesn’t.
I’ve got so many of the things laying around the office it’s not even funny. I’d do something like that, set for 5vdc or 6vdc.
I know it’s a bit spendy, but it’s also handy. It’ll work with many household things that run on batteries or the AC adapter.
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THat’s Great! Thank you for the information and the link, hell, what’s another $20 at this point and it is good to have in the future. Well, I’m going to go drop the pan and valve body now, I will repost this evening with my findings. I really appreciate you replies, I’m glad I found someone who has knowledge in this area. Much thanks, we’ll talk later.
Update:
I dropped the valve body in the transmission of my Lexus (not literally of course), hoisted the valve body and all the solenoids plugged into it onto my workbench. I also removed the transmission wiring harness that feeds these solenoids. This is what stumps the hell out of me…Everything tested fine, of course the only circuit and solenoid I’m now concerned with is the Linear or Shift Valve SLN Accumulator back pressure modulation (technical term). There is continuity on both wires going to this linear solenoid when testing end to end, the linear solenoid’s resistance is still a constant 5.5 ohms but there is one thing that is maybe a little strange…The directions for testing this solenoid say to have a variable voltage output and signals from the ECM to this solenoid typically switch back forth no more than 5 volts but the test section says apply battery voltage with a 10 watt bulb lead to this solenoid which varying the voltage to see that it contracts fully. Not wanting to fry the thing, I took your advice Tedybear315 and purchased the device from Radio Shack which allows me to vary DC current between 3.5 to 5 volts (Thanks very much!) however when I apply the full 5 volts the sound this solenoid makes is nothing like the sharp clicking of the shift or lock up solenoid, its more muffled and hollow and almost labored. I don’t know if its supposed to be this way or because I’m only applying 5 volts to it and maybe its supposed to operate up to 12 volts like the other solenoids? I also measure the amperage draw and it falls within specs for the voltage and ohms, I should have the new wire harness and linear solenoid here on Tuesday, God willing this will resolve my P1765 problem, if not then the only thing to do is send the ECM off to get repaired, I found a company called AES who seems very professional and the cost if around $230. I’m thinking about removing the ECM very carefully tomorrow and just visually inspecting the circuit board for anything obvious. These damn Gremlins are getting the best of me!
In case anyone wants in on this one.
I think that should cover some basics.
Judging by the testing. It looks like the solenoid has the actuator-valve–spring for tension.
So when the voltage is applied, the actuator moves in an outward fashion, pressing the spool valve against a calibrated spring. The ‘duty cycle’ (aka, waveform output) determines how much force is placed against the spring-and thus how far the valve moves.
So the test is just “Does it move” in the arrow direction. If the actuator is moving outwards and working against the spring–you probably won’t hear much of a ‘thunk’. But you should see it move in the arrows direction.
This component is not truly on all the way…or off all the way while you are driving down the road. They use the computer to control how far in/out (working with the spring tension against it) the valve is actually positioned at via a “Duty Cycle”. (Kinda like how a fuel injector works. The shorter the duty cycle, the less fuel/valve open time. Longer the duty cycle, valve stays open more and more fuel) In this case it looks more complex, but the principle is the same. When you do the test with the 10watt bulb and apply the voltage–that should move the actuator to the extreme position. The solenoid is apt to get a bit warm/hot while doing this, so just doing it for a second or two should tell the story.
I think working the flow chart is going to be your best bet. Checking other forums I found that from time to time dirty contacts at the computer itself where all these goodies plug in? Can also create issues. I’m reminded of the old ford EEC-4 test where our trainer actually said to “unplug and plug in the connector to the ECM 10 times to clean the contacts”.
I wish I could be of more help. General electronics I’m pretty good with. This one basically looks like it could stand to be hooked up to more precise tools (aka, someone like Scanner Danner with his PicoScope to “see” what the computer is actually doing-or not doing).
I’m hopeful that others can chime in on this one. This is about as far as my knowledge can take things at my end.
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THanks again for your input Tedybear315,
good detailed information about the duty cycle of the linear valve solenoid, to me the best way I can understand it is that this circuit and solenoid act as both a sensor and an actuator of sorts, I’m just praying for any reprieve at this point that by replacing the solenoid and wire harness will fix the problem. From what I’ve seen, tested and probed so far, it appears that my soldering and repair job to the wires worked which leads me to the unfortunate conclusion that something more sinister is at work here. I fear the ECM sustained some damage when this wire to the SLN Linear solenoid was severed, it appears to be a straight shot of wire between the ECM and the SLN/ Linear solenoid not leaving much in the realm of overload protection. As you noted, I certainly wish I had ScannerDan on speed dial, I’ve always wanted to get a PicoScope but they just cost way too much money to justify as I’m not a full time mechanic. The Linear Solenoid does move back and forth as described in the test procedure. If I make any new findings I will report back to this thread, I’m going to carefully remove the ECM today just for a visual inspection. thanks again for all your help Tedybear315!Update:
Upon removing the ECM, I unplugged the E9 Connector/Terminal to find it saturated with a red liquid, I can’t really surmise if its transmission fluid, or maybe even power steering fluid. I don’t think that this is normal and the affected SLN circuit appears to be in terminals other than the E9 so could this be affecting/causing my P1765 problem? Is this liquid normal? I’ve posted a rather crappy photo here as an attachment.
That’s the sad reality of todays automotive electronics. You need (to do the very tech stuff) some high end testing rigs and such to even test things.
Keep us in the loop on it. If the solenoid passed it’s testing, the issue is being triggered by something else. Wiring to the computer, dirty connector, computer itself. I’ve even read about issues with the engine tripping the code(s) and it threw the owner for a loop trying to figure it out.
Best wishes with it and good luck!! Let us know how you make out. In the mean while? Anyone else with ideas please post ’em if you got ’em!
S-
You certainly have been on a journey with this one. I’d say you were making good progress though. I think it was a good move replacing the harness as it sounds like it was getting beyond repair. I think some of your testing could use some work however. What I mean is that many times the solenoids are grounded to their mounts meaning that it would appear that they were shorted to ground when in reality that’s the way they’re suppose to work. I’ll admit that I don’t know the specifics for the vehicle you’re working on however. I did do this write up on how to deal with electrical problems however that you might find helpful.
http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems
That said the liquid in the PCM probably isn’t good. Perhaps it’s contamination from outside like something someone spilled on it or something. I suppose it could also be a failed component inside that might have leaked something out. It does however give credence to the theory that your problem is in the PCM in my opinion. Please keep us posted on your progress.
UPDATE!
I’m overjoyed to report that the P1765 Code has been completed resolved, erraticated! I want to say Thanks to Tedybear315 & Eric the Car Guy for your replies of helpful information and support! I received the new wiring harness for the transmission to solenoids on July 8th, however I freaked out when I compared the new SLN Linear Solenoid to my old one, the new one was shorter in length and had a completely different arrangement of port holes. I called Lexus parts out of Atlanta from which I ordered them from and explained everything to the parts manager “Demetrick”. He was sensitive and understanding to my fears that this wasn’t the right part (see photo attached) and told me to call him back the next day after he checked with the parts warehouse because there had been a part# change which means an alteration had been made of the original part. Demetrick was able to confirm only that yes, the new SLN Solenoid was shorter than the original but couldn’t confirm the difference in port holes. I went ahead and installed the new Linear Solenoid into the valve body (crossing my fingers). I wrapped all the solenoid wires in this really cool stuff called Xtreme tape which looks similiar to electrical tape but is self fusing and withstands temperatures up to 700F. This worked much better than the heat shrink tubing I had on it, my GF helped me to hold the valve body in place while I connected the throttle cable (almost impossible without a 2nd person), bolted it all back together and torqued to spec. This morning I put 1 gallon of Valvoline ATF for Multi cars (blue bottle). Just a quick note that the ATF by Valvoline in the blue bottle seems to resemble what came out of the transmission initially than the one in the red bottle which seemed much thicker and darker (labeled high mileage). I would recommend the Blue bottle multi-car ATF over the red bottle stuff. I installed a brand new battery (Gold Series from advanced), turned the ignition to the on position, connected my scanner and there were NO CODES! No pending codes either, my heart skipped a beat, I started the engine and still no problems. The engine/transmission vibrated a tiny bit but smoothed out within seconds of the ATF circulating. I took it for a nice long test drive down local roads and the high way and it shifts smoothly I have all gears again! The only slight thing I barely noticed was a tiny bit of intermittent vibration between 55 to 60mph. This could be because the trans needs a little more ATF, a wheel out of balance or more likely a worn tie rod. I couldn’t really isolate it but I’m not too concerned after all that I’ve been through. Oh, and Eric to respond to your reply, shift solenoids 1, 2 and lock up are grounded to their mounts just as you noted however the SLN solenoid which was the last big problem has a power wire and a ground wire that goes back to the ECM and the ECM monitors the duty cycle via the wire. I think I said it correctly… when I accidentally severed the power wire coming from the ECM going to this SLN Solenoid I was worried that this wire may have grounded out the current on metal and burned/overloaded that circuit of the ECM but it hadn’t thankfully. The red liquid in the ECM connector was a strange find, all I can chock it up to is some kind of melted electrical connector grease because it had no smell nor was it easy to wipe away. If this didn’t resolve the problem then definitely Eric, the ECM would be at fault here. Well, I have to go pick up my tools in the yard and try to find the elusive 10mm craftsman ratcheting wrench that disappeared 2 months ago, LOL.
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