Transmission and COMBI Help

Post by **bmdubya1198** » 29 Nov 2015, 15:02

I've been working through this on another thread, and I just posted this topic on Volvospeed, due to the extensive performance/technical knowledge, but obviously this is the most active Volvo forum, and probably the most helpful. Not that I don't appreciate everything so far, but I'm stuck, and I wanted to post this NEW topic to get the attention of others who may have experience with similar issues or may know a specific cause of this other than wires that aren't connected completely. I can't think through typing a whole new post, so I'm just going to quote what I have posted at Volvospeed. That topic is located here: http://volvospeed.com/vs_forum/topic/17 ... bi-issues/

Hello all

I am getting very aggravated by my car, because I've been trying to work out this transmission for the past three months now, and I keep getting to what I think is the solution, and then realizing that nothing is fixed.

I have been working through this on another forum, but it seems the Volvospeed community has more users and lots of technical information, and I would like to try to start with one simple (I say that now...) question...

Currently, I only have 3 codes logged for the Instruments on BrickDiag Free... 2-2-1 Speed Signal, 1-2-4 RPM Sensor Signal, and 1-2-1 Engine coolant temperature signal. What could these have to do with my transmission, and could these lead to the answer I've been searching for?

There are no other present codes. Previously, I had EFI-335 on VOL-FCR and 3-3-5 on BrickDiag, along with P1618 on Torque for Android using an ELM327 OBD-II bluetooth adapter, but none of those codes have come back. Other notable symptoms include no "up arrow" light on the cluster (not when starting, not when I hit the W button, not when in low gear, nothing.), bad jerk and drop in RPM when I shift from P to R, and starting in 3rd gear when in D (limp mode).

I have cut and re-tied/spliced several broken or twisted wires (car was in an accident, front pass. side impact, crushed some wires, but most have been re-spliced) with no changes. I have replaced both the TCM and the ECM just to test, also no changes (currently the ORIGINAL units are in the car). I had replaced the PNP switch just to test, and no changes.

In my original diagnostics using VOL-FCR, I had discovered that I cannot connect to AW50-42, and that is one of my main issues aside from my transmission not functioning properly. I am using a VAG-COM KKL cable to connect, by the way. I cannot connect to the transmission via BrickDiag_Free, either.

COMBI/Instruments was not giving me any response, either, in VOL-FCR. Like I said before, I get those three codes on BrickDiag, whether I have Yazaki or VDO selected.

I have checked just about all of the grounds that the accident may have damaged, including the one under the passenger side headlight, and they are all fine. That ground under the light was slightly frayed, but I cut the wires and re-soldered and crimped it into a new lug/ring/whatever you want to call it. Again, no changes.

Sorry for the long and somewhat scattered post, but I'm sure you can understand how frustrating electrical issues are. I will continue to check grounds for damage or bad connections, including the transmission ground (which I still need to find), but if anyone has any idea what could be an issue here, PLEASE share. I have also checked the transmission fluid, and it appears to be fine. I am 99% positive that this issue is electrical.

Car is a 1998 V70 GLT, AW50-42 automatic trans.

Post by **Ozark Lee** » 29 Nov 2015, 18:45

The RPM sensor and speed sensor have everything to do with the performance of the transmission. Without those signals it goes into limp mode since it can't make a decision on when to shift. The temp sensor, not so much on a Volvo. On my Chevy the transmission shifts later with a cold engine by design, to help the car warm up quicker, but I have never noticed that with my Volvo's.

Are your ABS / SRS lights on? Do those lights come on when the key is in position II before you start the car? Do the speedometer and the tachometer function properly on the dash? The speed signal is derived from the wheel sensors through the ABS module. If the module is bad then the speed signal often dies with it. The post '95 P80 ABS modules have pretty much a 100% failure rate due to the way they were flow soldered when originally manufactured.

What is strange is that the up arrow isn't flashing. Those codes should trigger both a CEL and the flashing up arrow and the car should be stuck in third while in drive. It will feel like you are dragging around a safe when you take off form a dead stop.

If you suspect wiring issues due to a collision then about all you can do is grab some schematics from here:

http://www.volvowiringdiagrams.com/

Try to find the correct schematic (the pagination is all screwed up on the scans), and go after it with an ohmmeter.

When you get the schematics get the '98, '99, and 2000 version. There are some pages missing on all of them but together they are fairly complete and the wiring didn't change between those years.

...Lee

Post by **bmdubya1198** » 29 Nov 2015, 20:03

Ozark Lee wrote:The RPM sensor and speed sensor have everything to do with the performance of the transmission. Without those signals it goes into limp mode since it can't make a decision on when to shift. The temp sensor, not so much on a Volvo. On my Chevy the transmission shifts later with a cold engine by design, to help the car warm up quicker, but I have never noticed that with my Volvo's.

Are your ABS / SRS lights on? Do those lights come on when the key is in position II before you start the car? Do the speedometer and the tachometer function properly on the dash? The speed signal is derived from the wheel sensors through the ABS module. If the module is bad then the speed signal often dies with it. The post '95 P80 ABS modules have pretty much a 100% failure rate due to the way they were flow soldered when originally manufactured.

What is strange is that the up arrow isn't flashing. Those codes should trigger both a CEL and the flashing up arrow and the car should be stuck in third while in drive. It will feel like you are dragging around a safe when you take off form a dead stop.

If you suspect wiring issues due to a collision then about all you can do is grab some schematics from here:

http://www.volvowiringdiagrams.com/

Try to find the correct schematic (the pagination is all screwed up on the scans), and go after it with an ohmmeter.

When you get the schematics get the '98, '99, and 2000 version. There are some pages missing on all of them but together they are fairly complete and the wiring didn't change between those years.

...Lee

Thanks, I'll look over these diagrams.
The ABS and SRS lights are not on, but they do come on momentarily when I turn the ignition into position II. I had cleared the SRS codes that the car had (for the seatbelts that I had replaced). I'm not sure if this is normal, though I assume it is, but when I am connected to the ABS on BrickDiag or VOL-FCR, the ABS light flashes, then when I disconnect, it stays solid for a few seconds before turning off.
As far as I know, the tach and speedo work fine. They seem accurate any time I've tried them. The car definitely feels like it's pulling a safe when I take off from a stop. Like I said, in reverse it feels fine, but not in drive.
I am probably going to test each wire again with the ohmmeter. Do you happen to know if the ignition needs to be on or off, and what reading I should be looking for? If I did it correctly last time, I got reading of 1-3 ohms, using the 100 ohm option on my multimeter. That was on the front side of the ECU board, on the back side, I got 0, which is what it is supposed to be, if I'm not mistaken. This is going by the few pins that I tested. I have a pinout diagram, and it showed an A side and B side, but I'm not sure which is which. I should probably review that.
I've been concerned about the up arrow light, too, seeing as I haven't seen it on once since I bought the car 3 months ago.

Post by **Ozark Lee** » 29 Nov 2015, 20:38

If the up arrow light does not come on when the W button is pushed then chances are it has either been removed or it has burned out.

For continuity readings I test things end to end ( it usually takes an additional wire to get both leads hooked up and I look for zero ohms. On a digital meter a few tenths of an ohm is essentially zero. On an analog meter there is typically a zero adjust that you can set the meter to zero with the leads shorted together.

If you get zero ohms end to end and you don't get zero or low resistance to ground (both ends of the wire under test unhooked) then the wire is good. If you get high resistance or you get a low resistance to ground then the wire is damaged. If it is damaged you can either try to find the bad spot or just run a new wire. and splice it in near the ends of the connectors. Many of the wires have an intermediate junction point between their ultimate ends and you can test the wire in segments. The junction points are very well documented in the schematics.

Electrical problems are a bear to find but once found they are usually easy to fix.

...Lee

Post by **bmdubya1198** » 30 Nov 2015, 18:31

I'm probably going to get some bulbs and pull the cluster, hopefully it's just the bulb and not some other crazy wiring problem.
Other than that, does anyone know where I can find a TCM pinout for AW50-42? I'll check my 1998 70 Series PDF again, but I can't find one otherwise.

Post by **Ozark Lee** » 30 Nov 2015, 18:37

I'm sure someone will post it for you but unfortunately it can't be me since I am a moderator. We used to post schematics all the time but Volvo got touchy about it. Someone else that isn't a moderator can post them but I can't.

...Lee

Post by **bmdubya1198** » 01 Dec 2015, 10:47

I'll take a look around. I saw a page with wiring diagrams on this website that was shut down because Volvo didn't like that it was there. I guess they feel the need to charge you for all that.

Post by **bmdubya1198** » 11 Dec 2015, 13:06

I pulled the cluster the other day and replaced the bulb for the up arrow light. Still doesn't come on upon ignition on or when I press the "W" button on the transmission. I am assuming that means it's also a wire.

Anyway, just in case anyone can help me answer these questions here, I am going to post what I just posted on my Volvospeed thread:
Just a quick update, and a couple more questions...

I tested some pins today. I was told that B15 on the TCM connects to B26 on the ECM. That doesn't appear to be the case on my car, but if it is, I am reading the TCM pinout diagram incorrectly. I don't actually have a TCM pinout, just a small diagram within a blow-up diagram which shows only one half of the pins. I assumed that the B-side was just a reverse of the A-side I assume it's showing me. I know, real scientific approach...

So, on to what I was saying about testing the pins. When I tested the ohms between ECU B26 and presumed TCU B15, I got nothing. No response at all. I also tested B26 to B28 (signal ground). I got reading between 138-140 ohms. I was advised in this thread (https://www.matthewsvolvosite.com/forums ... 4&start=28) (post #4) that that reading should be between 0-3000 ohms.

I had mentioned that I got a code from COMBI via BrickDiag that said something about the coolant temperature sensor. I saw that pin B23 on the ECU was the ECT sensor to COMBI wire, so I put one end on there and one end to each of the wires on the ECT sensor. I got a reading of ~117 ohms for each wire. Not sure if that's good or bad (this is one of my questions).

I'm not sure what pin this is on the TCU (because of the absence of a TCU pinout), but on my little diagram (which I will link soon) it seems to be B30. I tested this pin against B26 on the ECU (red wire, appears that this is the only one connected between the 2 modules) and I got 0 ohms, meaning a complete connection.

Then, there is one more wires I have questions about. It is a blue wire with a black stripe, running from the TCU's B15 pin, and possibly the other end of the wire connecting at the ECU's B25, but I can't confirm that it either connects at that exact pin or if it's just another blue/black wire. Anyway, the connection at the TCU board looked loose, so I tested it with the multimeter, and the ohms zeroed out, meaning it is making a good connection. Then I tested the B15 TCU pin against the ECU's B25. Ohms didn't move, so either that wire is disconnected, or they have nothing to do with each other (I have a feeling it is the latter, but I won't know until I test the rest of the pins on the ECU against the TCU's presumed B15).

I was, of course, looking for damaged pins, and I found a few that were iffy, but not exactly "damaged," per se. I will try to remember to post pictures later today or tomorrow.

That's what I got for now, and if anyone has any input at all, PLEASE share, as I appreciate every bit of information I can get.

Also, I tested everything on my multimeter's "2000k" setting under the "Ohms" category. It's just the basic Cen-Tech Harbor Freight multimeter.

Documents I've been using...

Dilemma's Motronic 4.4 PDF (with ECU pinout) https://web.archive.org/web/20110831121 ... %204.4.pdf

Volvo S/V/C70 Wiring Diagrams https://www.matthewsvolvosite.com/downlo ... _Coupe.pdf
(I want to say the page I have is in the 200s, and the PDF isn't loading too quickly for me right now. It is titled "AW50-42 electronically controlled transmission Fenix 5.2, Motronic 4.3/4.4" and has a diagram of both the engine bay, dashboard, and transmission, highlighting key components, TCM being 4/28)
...If anyone would like to see the pictures, I posted them on my Volvospeed thread.

Post by **bmdubya1198** » 12 Dec 2015, 18:33

I have been advised by a Volvospeed member that my post was a little disorganized. I can actually agree with him, as I always overdo it, making sure every detail is included... probably multiple times. Anyway, here is a more simple layout of information that someone may be able to help me out with:

ECU B26 -> TCU B15 No response.

ECU B26 -> TCU B28 (signal ground). 138-140 ohms. I was advised in the previously mentioned thread (post #4) that that reading should be between 0-3000 ohms, so this should be OK.

ECU B26 -> TCU B30 (Unsure if it is B30, need pinout diagram), 0 ohms, meaning a complete connection. This is a red wire that looks like the only connection between the 2 modules.

ECU B25 -> TCU B15 Ohms didn't move, so either that wire is disconnected, or they have nothing to do with each other (I have a feeling it is the latter)

ECU B23 -> ECT sensor, so I put one end on there and one end to each of the wires on the ECT sensor. I got a reading of ~117 ohms for each wire. What is a correct resistance? and could this reading suggest a short?

Also, not sure if I included this, but the battery was disconnected at the time.

Post by **Ozark Lee** » 12 Dec 2015, 19:33

ECU B-26 --> TCU B-15 should read zero ohms

ECU B-26 --> TCU B-30 should not read zero ohms. I can't say with any certainty what it should read since the modules are schematically a black box but TCU B-30 is ground.

What this suggests is that the wire between ECU B-26 and TCU B-15 is cut and shorted to ground. It could be another wire that it is shorted to or it could be something on the case but likely the former since the ECU cage is plastic.

Can you post up a picture of the ECU / TCU cage? I'm trying to visualize the extent of the collision damage that would tear up the wiring inside the cage.

Have you removed the case from around the ECU / TCU modules? Doing so will reveal wiring under the connectors and some things may become very obvious when you see the wiring bundle there. If you do have it removed post up pictures of that as well.

The -117 Ohm thing suggests that there is still battery voltage present since there really is no such thing as negative resistance. ECU B-23 goes to the temp gauge, not the ECT sensor.

...Lee