Car: 2005 SRT6 Coupe 70,400miles

No previous transmission issues, always been smooth and fast.



Current Issue:

Was driving normally, no hard pulls or anything just casual driving. After about 20mins of driving I went to bump shifter into manual mode and nothing happened. I tried shifting up and down gears to no success and dash indicator still said D instead of a number for the current gear. About 30secs later hit a stop light and tried shifting into park and back to drive then trying to get into manual mode still no luck. Light turned green and the car made it 60yds before I lost all power to the ground. No loud noises or anything it was like suddenly I was in neutral. Pulled over and tried shifting into and out of park multiple times turning the car on and off the dash indicator stayed on D and eventually turned to a black square and locked the shift lever in Park and threw a CEL. I tried checking wiring and connections at the RCM as well as disconnecting the battery and letting it sit overnight with no luck. Scanner showed codes P0600, P0715, and P0720 all at once. I can get the car out of park by sticking something in the little trap door by the shifter but it never sounds like anything tries to engage and both reverse and drive act like neutral. I can rev the engine and push the car but nothing starts to engage so I had to tow the car home. I tried wiping the codes and issue is still present with black square for gear indicator. Never spilled anything in the car. Not sure if its relevant but for a while I had an intermittent code P0410 that would trip the CEL sometimes but hasn’t been present for several months.

From the OBD Scanner that was borrowed.

P0600 “SLA (Shift Level Assembly Module) CAN Message Incorrect / CAN Message Missing”
P0715 “Input Sensor Mismatch”
P0720 “CAN BUS Circuit”

I have seen threads of people with similar issues and one of the codes, getting fixed by either replacing RCM, the SLA shift assembly, Brake interlock solenoid, or the transmission conductor plate. However, I have not seen anyone throw all these codes at once. Also everyone with similar issues always seems to be able to drive the car still with the worst case being stuck in limp mode before fixing, I haven’t seen anyone that has no engagement in gear like I do.

So Im not sure where I should start looking first? I was also wondering if there is a way to test the functions of each part individually, especially the SLA I cant find anything on how to check if its good or bad everyone seems to just replace them and hope their issues resolve.

Thanks in advance!! Any help is greatly appreciated.

 

P0410 is often rectified with a new RCM. Some of your other problems also sound like RCM problems. Best to get a new one and mail your old one to tighed1@hotmail.com for repair. It will also be an improved RCM than the original.

P0715 and the P0600 can be related as they indicate wiring problems between the transmission and the Transmission Control Module (TCM). P0715 can also be triggered by problems with the transmission conductor plate.

First things first. Check battery voltage for fully charged battery. (Bad/low battery causes all kinds of trouble) If that's okay get a new RCM so we are certain that isn't contributing to the trouble. (Send your old RCM off for repairs) If you still have problems then start trouble shooting P0715. There are several causes to that will trigger the code and you haven't indicated exactly what the DTC refers to. You will find trouble shooting step by step in the service manual available for free for download on the this forum in documents. If you don't want to go that route go straight to replacing the conductor plate and hope for the best. Replacing conductor plate is also the most expensive step to take as you will also need new filter, new gasket and fluid for the transmission.

The heated seats and the Heater A/C fan speed is unrelated to the driveability of your car.

 

Thanks for the reply! I wasnt sure if any of the Ac/heat wiring tied into any of that stuff. I have edited the original post to only include relevant information as well was the DTC from the scanner.

 

New RCM module https://www.autohausaz.com/pn/MB-1705450305

 

To quickly check if it's not a broken wire in the CAN BUS, you could measure the resistance between pins 11 and 4 on connector C4 of the ECU (I might be wrong on the connector number, but you can check it in the service manual). With the car off, key out of the ignition, it should read roughly 60 ohms. If it reads 120 ohms, you probably have a CAN BUS wiring problem. Hopefully, it's just as simple as a bad RCM.
Good Luck,
-Jerry

PS. sometimes with a CAN BUS error, it will throw codes saying that it can't communicate with the HVAC module.

 

Thanks for the response! Thats very helpful in eliminating potential issues! I will try this as soon as I get some time. I just sent off my RCM today to DJ in Arizona to ensure that the RCM isnt causing any issues, and maybe I will get lucky and that will fix my issues. . .

 

Hi Jerry,
I was curious if the CAN BUS had just the single in put to the PTCM that you mentioned or perhaps there where more on other connectors, so I checked the 2008 Service manual this morning. Turns out the CAN BUS is connected to the PTCM at just that one location on connector C4. So measuring the resistance of just that one connector tells the story quickly as to CAN BUS integrity; very good thing to know. 60 ohms give or take a little is good. The CAN BUS runs to a number of splices on different circuits but they all find there way to the PTCM via just those two pins. However, correct me if I'm wrong because I did not open the car and actually check the wiring at C4, but the 2008 service manual shows pin #1 as + and pin #11 as - CAN BUS vice the pins you mentioned.

Thanks for posting that info. It is very helpful.

 

Hi Zip,
Thanks, You're correct, I checked and it's actually pins 1 and 11 on C4 of the PTCM. BTW, to get 60 ohms you need to back probe the C4 connector while it's still connected to the PTCM. If you disconnect from the PTCM, and measure from the front of the connector you should get 120 ohms, and if you measure the pins on the PTCM, you should also get 120 ohms. Unfortunately, my experience was gained the hard way - the CAN BUS splice (S116) in the engine compartment under the brake booster failed, but before I figured that out, I did a lot of diagnostic work. (Not to advertise my posts, but I have a post called "No Crank...." that has all of the voltages and resistances that I measured before I found the bad splice in the CAN BUS. Some other useful info in there is how to manually run the fuel pump or the starter motor.)
-Jerry

 

I read your other "No Crank" thread; lots of time/work but that's what it takes now to keep these aging cars up and running. You wont find a commercial shop willing to put that much effort into properly sorting out a problem.

I just spent ten days finding and to verify my PTCM problem ( It wasn't switching to ground when necessary on O2 circuit). Good work! Thanks for the info; very helpful.

 

Update I got the RCM put back in and as soon as I plugged in the battery the hazards or running lights were flashing but no indication on dash that the hazards or anything was on. I started the car and it stopped, however my initial problems still persist. I am planning on checking the ohms of the CAN BUS circuit at the PCM C4 connector but if all is well there, not sure if I should move towards SLA or Conductor plate?

 

Thanks for getting back to us. You will need to download the service manual if you haven't already. It will have wiring diagrams, splice locations and connector pin outs as well as trouble shooting the DTC you have.
If you still have the siren/alarm hooked up under the windshield cowl, I would disconnect that before digging in any deeper than the C4 connection at the PCM. Flashing lights can be triggered by a bad/old siren which involves the anti theft system which can prevent the car from starting.
GOOD LUCK.

 

Well I disconnected the alarm siren. No flashing lights when I hooked the battery up. I measured the Ohms at C4 of the PCM, using my cheapo multimeter I get about 87ohms backfeeding the plug and closer to 160 with the plug removed on the front of the plug and the pins on the actual PCM so I assume thats in spec and my meter just reads a bit high? I have tried reading the manual but I only have the digital version from the document library and which doesnt show me page numbers for some reason and is miserable to navigate without them. Kind of at a loss on what to do next. I kept seeing in the manual to do things like perform “Transmission Verification Test” but couldnt find anything about what that even is. I still have no CEL since wiping them after multiple start ups but I cant drive the car at all because I have park and 3 neutrals but the dash only shows that black square.

 

Try reading this thread:
No crank black square in Instrument Cluster

 

Srt6exy; Do not disbelieve your resistance measurements; They are telling you something.
Read post 8 above and the one linked to by M60A3Driver.
Not easy to grasp, but I'm thinking the answer to your problem is in those posts.
I totally get the difficulty of using the digital service manual. You can find paper service manuals on ebay. I bought a set a couple years back. Get the 2005 paper if you can find it as it will have SRT6.

 

I may have made a discovery, Im reading to try and find the cause but have not yet found my answer.

Below are some measurements Ive been able to take so far. All measurements are taken with the battery negative cable off and module plugs unplugged so readings are from “plug to plug” so to speak. I also attached a table made from @red_2005_convertible chasing a similar issue. You will notice my measurements between the SKREEM and TCM as well as the SKREEM termination are not correct.
Some measurements may be off slightly as I am using DIY probe extensions to fit inside these tiny plugs and every now and then they cause the readings to go up around 4ohms.

PCM C4 P1 - TCM L 126ohms

PCM C4 P1 - TCM H 8ohms

PCM C4 P11 - TCM L 1ohm

PCM C4 P11 - TCM H 120ohms

PCM C4 P1 - PCM C4 P11 120ohms

TCM H - TCM L 120ohms

SKREEM P1 - TCM L 2ohms

SKREEM P2 - TCM L 11.2kohms

SKREEM P1 - TCM H 11.2kohms

SKREEM P2 - TCM H 1.2ohms

SKREEM P1 - SKREEM P2 11.2kohms

 

Hi Srt6exy,
I think you are getting close. Did you back probe these connectors, or were they disconnected while you probed them? Like your first line PCM C4 P1 to TCM L, were both connectors disconnected, or only the TCM? If just the TCM connector was unplugged, and all others plugged in, you should read ~60 ohms. Have you tried measuring the resistance between PCM C4 p1 and p11 into the PCM module (the C4 connector disconnected from the PCM, and just touching the pins coming out of the PCM) or SKREEM P1 and P2 with the connector disconnected and into the module. Assuming that your PCM connector is connected, TCM and SKREEM connectors are disconnected, it looks like you have an open between the SKREEM and the PCM on the CAN BUS. Your reading from PCM C4 P1 to TCM H (8 ohms) looks a little high since this should be a straight shot along one wire like PCM C4 P11 to TCM L (1 ohm) => you might have a damaged wire between PCM C4 P1 to TCM H maybe as S123. And your measurement from SK P2 to TCM L suggests the issue is on the side of splice S123 going towards the PCM. To confirm my guesses, print a copy of the CAN BUS wiring diagram in my post, and write the resistances you measured on the different legs connecting the different pins. The 11kohms is the isolation resistance between pins on the other modules. I also see now that I should've posted what the nominal values were after I fixed my issue so it would be easier to identify the problem. If it really is damage on the wire between S123 and the PCM, that should be fairly easy to fix by running a twisted pair between the PCM and the CAB.
Good Luck
-Jerry

PS. Finding the splice in the engine compartment can be a bear, but I think S123 is on the top of the firewall, under the cowl, midway between the PCM and CAB, or it could be in the fuse box.

 

Battery Cable off for everything.
When I was measuring things between the PCM and TCM both were unplugged and I was measuring at the front of the plugs themselves. The SKREEM was still plugged in at that time.

After that I started taking apart the dash to get to the SKREEM so the measurements between the SKREEM and TCM were both unplugged as well as the PCM still being unplugged.

I did also try measuring the PCM while plugged in and I wanna say it was 61 or 62 ohms but I forgot to write that down in my notes.

 

Hi Srt6exy,
Okay, that changes things, but I do think that 8 ohms between PCM C4 P1 and TCM H is kind of high. Not sure which measurement falls into this, but if you have the SKREEM and PCM plugged in, you should measure ~60 ohms between the H and L pins on the unplugged TCM connector. If only the SKREEM or the PCM is plugged in, you should measure around ~120 ohms between the H and L pins on the unplugged TCM connector. (Negative Battery cable off, key out of the ignition.) Since you have the SKREEM out, measure between pins 1 and 2 on the module - it should read ~120 ohms. Also, since you have the TCM out, have you noticed any transmission fluid around the TCM or in the TCM module connector? (use a white cloth/tissue and wipe around there). Sometimes, which I think is pretty insane, the transmission connector leaks, and the fluid wicks up the cable to the module, shorting out the module.
-Jerry

 

I think all those measurements were in my list already including skreem 1-2, however Im gonna remeasure them all tonight if I get time now that all 3 modules are unplugged and see what I find. The help youve provided so far is immensely appreciated, it wouldve taken me so long just to get to the point Im at now! So thanks for that!! Hopefully I cant find whats causing the bad measurements and get access to it, Id love to not need to take apart my center console and everything else to get to the SLA but will if I have to.

 

Ok I redid all my measurements and made tables for ease of reading them. ALL measurements were done with the negative battery cable removed. One table shows all modules unplugged, one shows just the PCM plugged in, the other shows just the SKREEM plugged in. I am not sure what to think, once again any help is greatly appreciated!