llhat Posted October 14 Share Posted October 14 I've searched and found prior issues but not exactly... and yep this is a long arsed post... 1989 Comanche 168k 4.0 renix (stock) some time ago, transmission started not shifting, and not taking off in 1st gear (sluggish start). I use vehicle sparingly and just placed shifter to 1 and manually shifted, and also noting no converter lock up. Some other issues got in the way and now started diagnostics using the tips posted elsewhere. Have found some other info online.. one is here https://itsajeepworld.com/wp-content/uploads/2019/11/auto-trans-diagnosis.pdf but of course do not have the scan tool! So far: Removed lower dash panel to better access fuse panel and TCU Checked, inspected the 7.5 trans fuse in fuse panel ( back probe with 12v test light to ground, both sides of fuse, OK) removed and checked continuity OK Checked, inspected the 10 trans fuse in the in-line holder ( back probe with 12v test light to ground, both sides of fuse, OK) removed and checked continuity OK Under hood, found the gray connector and separated, could see 'nothing wrong' with internal connections so, first question... the connector side with MALE pins, can you confirm it is From the TCU or is it to Transmission? a FSM diagram shows male pins from TCU and female to the transmission I used an on-line manual reference above and found this diagram to identify the pin-outs. 7way.pdf the line of 3 pins, center pin is B, I checked continuity between this pin and negative battery terminal .4 ohms, so that is reaching ground. I tried probing between this same pin and others, no continuity to any So proceeded to female side 7way female.pdf used probe to check from middle pin on 3 row to battery.... no connection. I also probed to what should be the transmission solenoids looking for 12-13 ohm range... Get open circuits. actually same as the male side, no continuity to any cavity to B I was HOPING to find an open SOL 1 before i dive into the transmission internal connections... but with nothing, at an impasse What i have YET to do is probe from Center female on 3 row to Engine/Transmission body... thinking maybe internal ground connection in transmission. any assistance appreciated... and what am i overlooking? I have not tried plugging everything back up and test shift/ take off. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 10 hours ago, llhat said: so, first question... the connector side with MALE pins, can you confirm it is From the TCU or is it to Transmission? a FSM diagram shows male pins from TCU and female to the transmission The question here is do male pins go to Transmission or do they go to Engine Control Harness. I can't tell from the photos, but one side goes down to the trans. 10 hours ago, llhat said: the line of 3 pins, center pin is B, I checked continuity between this pin and negative battery terminal .4 ohms, so that is reaching ground. I tried probing between this same pin and others, no continuity to any I think you're talking about the male pin side of the connector. If true, this side goes to the Engine Control Harness. More Info: _mj1988electricalmanual_1.pdf Link to comment Share on other sites More sharing options...
llhat Posted October 15 Author Share Posted October 15 thank you for the response. i have a hard copy of the manual you attached. so confirming Male pin side of C114 goes to TCU, not the transmission. Pin B is the ground and there's continuity to the negative battery terminal. Female side of C114. Probing mating of pin B and any of the solenoid female cavities I get nothing... that is the present confusion. Solenoids 1, 2 and 3 ground to the internal body of the transmission... so, next will be a test of female cavity b to engine/transmission ? I also have found in other manual a through-connector to transmission body, I think near flywheel on passenger side. One now has to believe the harness is bad... which is strange in itself (scratching my head) I'm now guessing a pan drop is in order and probing the connector from s1, s2, s3 to the female side of C114 What would be of course helpful would be the cavity on the diagnostic port (which one) and could it be probed to see if +12v is being sent to solenoid from the TCU sure would like to get it fixed, tired of shifting manually. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 50 minutes ago, llhat said: Female side of C114. Probing mating of pin B and any of the solenoid female cavities I get nothing... that is the present confusion. Should read the solenoids if all testing was done on the same side of the connector. 52 minutes ago, llhat said: I'm now guessing a pan drop is in order and probing the connector from s1, s2, s3 to the female side of C114 Tough call here. Seems to be the next step. 54 minutes ago, llhat said: What would be of course helpful would be the cavity on the diagnostic port (which one) and could it be probed to see if +12v is being sent to solenoid from the TCU Best you can do here is check for voltage at the TCU. C234_D14 - Hot at all times - (D1_5) C234_D16 - IGN SW Run/Start - (D2_4) Link to comment Share on other sites More sharing options...
llhat Posted October 16 Author Share Posted October 16 thanks for that and an 'update' yesterday i modified the pins on a cheep multimeter so they would insert into the female side of c114 (thinking not getting connection was reason for not being able to test solenoid windings at the connector) no change. Found in some info there's a thru-connector on transmission for the wiring to penetrate the transmission case. I was going to raise vehicle on my lift to check this out, but experienced a hydraulic line failure.... *&%$& ... pretty much too old to crawl around on floor, so this will be on back burner... moving on to other tasks on MJ... I know i have power to TCU... and as a hail mary yesterday I removed 'cover' from TCU to examine board for any obvious blown resistors or caps... nuttin Out of all this, it is leading me to a harness failure... which to me is 'strange'... but certainly murphy's law prevails. can't see how it would just fail again, thanks for those pin-outs... Is there a method on the D1/ D2 for testing of signal "to" the solenoids? Link to comment Share on other sites More sharing options...
Crash Posted October 17 Share Posted October 17 If you really need to drive it you can shift manually. I'd maybe see I'd you could get another TCM to try. Link to comment Share on other sites More sharing options...
llhat Posted October 18 Author Share Posted October 18 thanks, i have been driving/ manually shifting. about to the point of investigating again, have some other tasks to handle. I am still perplexed that I cannot get a solenoid reading through the connector.. and when i get my lift fixed I will just drop the transmission pan and get some long leads to test from connector terminal to the solenoid connector. I found in giggle search the part number for the solenoid harness, but of course long discontinued.... not even seeing anything for used ones out there. I will also confirm 12v at the tcm connection. I have a new NSS, but do not think that is anywhere near the issue. grasping for straws. Link to comment Share on other sites More sharing options...
llhat Posted October 18 Author Share Posted October 18 On 10/14/2024 at 10:50 PM, Ωhm said: Best you can do here is check for voltage at the TCU. C234_D14 - Hot at all times - (D1_5) C234_D16 - IGN SW Run/Start - (D2_4) Ok, tried this today... believe i had the correct terminals anyhoo, but with C234 unplugged from tcu negative to metal dash panel, positive probe to face of D14 no volts switch on, positive to D16, no volts. Have voltage to both sides of 10amp fuse What feeds D14/D16 ? (i did not test diag1 pin 5 or diag2 pin 4... wish i knew someone with a scan tool for renix close... Link to comment Share on other sites More sharing options...
Ωhm Posted October 18 Share Posted October 18 1 hour ago, llhat said: Have voltage to both sides of 10amp fuse Is this that fuse? 1 hour ago, llhat said: What feeds D14/D16 ? (i did not test diag1 pin 5 or diag2 pin 4... D1_5 - Fuse Link G D2_4 - Ignition Switch (ON/START) Link to comment Share on other sites More sharing options...
llhat Posted October 18 Author Share Posted October 18 yes, and the fuse has continuity and checks 12v to ground on both sides of the fuse (the top of the fuse has a window that allows access to a probe. the 7.5 amp fuse in the fuse panel also checks OK. Link to comment Share on other sites More sharing options...
Ωhm Posted October 18 Share Posted October 18 Using battery ground, check D1_5 (Hot at all times) for voltage. Link to comment Share on other sites More sharing options...
llhat Posted October 20 Author Share Posted October 20 again Ohm, thank you for the response. today voltmeter (fluke) negative to negative battery terminal Diagnostic 1, Pin 5 Ignition OFF 12v confirmed Ignition ON Diagnostic2, Pin 4, 12v confirmed also checked reference voltage at TPS (square terminal) based on prior TPS checking instructions... OK for reference voltage and output D to A and D to B next... i have found on evilbay a few TCU, but NO one indicates if there good or not... and there's a difference in mounting brackets some the bracket is offset to the side, mine is on centerline of unit. Link to comment Share on other sites More sharing options...
Ωhm Posted October 20 Share Posted October 20 Best you can do here is check for voltage at the TCU. C234_D14 - Hot at all times C234_D16 - IGN SW Run/Start Link to comment Share on other sites More sharing options...
llhat Posted October 20 Author Share Posted October 20 with c234 plugged in to TCU and back probed or unplugged and from face of connector? not sure when i will sign back in... Link to comment Share on other sites More sharing options...
Ωhm Posted October 20 Share Posted October 20 Technically both ways should have worked, but since were here, disconnect C234 from TCU and probe at the C234 connector. This will help make sure vehicle wiring is GOOD. Link to comment Share on other sites More sharing options...
llhat Posted October 21 Author Share Posted October 21 22 hours ago, Ωhm said: Technically both ways should have worked, but since were here, disconnect C234 from TCU and probe at the C234 connector. This will help make sure vehicle wiring is GOOD. Connector 234, detached from TCU negative to body ground, my probe would not enter on face of connector, so back probed D14 12.6 volts ignition switch ON D16 11.6 volts (fluke meter) also checked D7 continuity to ground. OK. Again, thanks in advance for your troubles. Next? Link to comment Share on other sites More sharing options...
Ωhm Posted October 21 Share Posted October 21 On 10/14/2024 at 9:47 PM, llhat said: I'm now guessing a pan drop is in order and probing the connector from s1, s2, s3 to the female side of C114 Need to find out why you can't read solenoids values at C114 (Transmission Side). Link to comment Share on other sites More sharing options...
llhat Posted October 21 Author Share Posted October 21 thanks again, i believe that is the path forward, but it will have to wait until i get my lift functioning again, to old and fat to work on the ground or concrete. I did just now pull apart C114 and again on female side (to transmission) could not get a read between "B" (ground) or G, F, or E I CAN see the edge of the terminal and have confidence i am contacting the terminals on the face of the connector. it is almost impossible it seems to back probe those on that connector. I do wonder a bit if there's a way to verify @ c234 C16 to D7 for S1, C15 to D7 for S2, C14 to D7 for S3 ? C16 is output from TCU S1 through C114, D7 is ground. Just a wondering how that stationary cable could just go 'bad' from C114 to transmission... Can understand if maybe one of the solenoid wires inside the case deteriorated inside the pan and 'poof' but all 3?? Link to comment Share on other sites More sharing options...
Ωhm Posted October 21 Share Posted October 21 1 hour ago, llhat said: I do wonder a bit if there's a way to verify @ c234 C16 to D7 for S1, C15 to D7 for S2, C14 to D7 for S3 ? True. With C234 disconnected and C114 connected, solenoid continuity can be check for each of your solenoids. Link to comment Share on other sites More sharing options...
llhat Posted October 22 Author Share Posted October 22 21 hours ago, Ωhm said: True. With C234 disconnected and C114 connected, solenoid continuity can be check for each of your solenoids. ok, now maybe something to get out of the rabbit hole, C234 disconnected from TCU, C114 connected under hood. C234 terminal D7 continuity to chassis ground ( door hinge for negative) C234, Backstab D7, C16 = 15 ohms C234, backstab D7, C15 = ~14 ohms C234, backstab D7, C14, 13.5 ohms I still cannot explain 'why' no continuity when checking female side of C114, and of interest C114 cavity B will not check to ground continuity. but i have not backstabbed C114 on any terminal. but at C234, it would seem the solenoids are 'ok' and the harness to the transmission and solenoids is 'ok' what conclusions can be now obtain, or next test ? Link to comment Share on other sites More sharing options...
Ωhm Posted October 22 Share Posted October 22 49 minutes ago, llhat said: next test ? Still using disconnected C234, two (2) voltage tests. KEY ON C234_C9 to D7 when Gear Selector is set to Drive. C234_C8 to D7 when Gear Selector is set to 1 - 2. Link to comment Share on other sites More sharing options...
llhat Posted October 22 Author Share Posted October 22 i understand where you are going. these are telling the TCU 'what i want to do' will test tomorrow and report question.. C9 and C8 fed from NSS? I will look at diagram while watching tv tonite. thank you! Link to comment Share on other sites More sharing options...
Ωhm Posted October 22 Share Posted October 22 4 minutes ago, llhat said: C9 and C8 fed from NSS? Yes. Do your backup lamps work when REVERSE is selected? Page71. Link to comment Share on other sites More sharing options...
llhat Posted October 23 Author Share Posted October 23 today's test. Key ON C234 not connected to TCU No, BU lamps not illuminating Gearshift "1" position c234 D7-C8 11.8v (backstab) Gearshift "D" position C234 D7-C9 no voltage would make assumption TCU not getting signal for D position, and running shift logic engine starts only in P or D lever position. I have a NSS here, (new, evilbay procured) also making assumption it is correct (taiwan) noting the 8 cavity female terminal has only 6 terminals active cavity D & F are blank. do not know 'when' i will install it, or go through the 'rebuild' of the original switch. http://gojeep.willyshotrod.com/HowtoNSSrebuild.htm removal is necessary for either path. thoughts? Link to comment Share on other sites More sharing options...
Ωhm Posted October 23 Share Posted October 23 3 hours ago, llhat said: I have a NSS here, (new, evilbay procured) also making assumption it is correct (taiwan) noting the 8 cavity female terminal has only 6 terminals active cavity D & F are blank. True. 3 hours ago, llhat said: removal is necessary for either path. Seems like NSS needs some looking at. Link to comment Share on other sites More sharing options...
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