DIASPAR Posted September 25, 2007 Report Share Posted September 25, 2007 I posted a month ago on this problem (jumping in a bit late)...http://volvospeed.com/vs_forum/index.php?s...92&hl=p1618and after the car began showing other ABS symptoms (ABS light, flashing UP arrow, etc) I ordered a rebuilt ABS from Victor.Received the rebuilt ABS from Victor yesterday - easy installation, followed instructions, car w/new ABS runs quick "test" at 14 mph as advertised - but the CEL still stays on. Code reader gives me back my old friend P1618. Clear the code and it comes right back, within seconds of starting the car.So - what I guess I've got is a multi-symptom / multi-cause problem which has been partially fixed by installing the rebuilt ABS.Returning to my original hypothesis on this - several old posts have listed the description for P1618 as:P1618 VOLVO Cable fault between AW 50-Q2 TCM and Motronic 4.4 ECM (MIL lamp lights) orP1618 VOLVO Fault in Lead Between AW 50-52 and Motronic 4.3 (MIL Requested) which translates loosely as: "Broken Wire" or "Dirty connector"MY QUESTION(s):Does anyone know where the cable/connector(s) between these units are? How about a Pin-out on these connectors? Thanks - anything but a trip to the dealers - (please!) Link to comment Share on other sites More sharing options...
evilb Posted September 25, 2007 Report Share Posted September 25, 2007 I believe the ECU and TCM are both located in a plastic box behind the passenger headlight. You can pull them out and clean the connectors. Link to comment Share on other sites More sharing options...
DIASPAR Posted October 1, 2007 Author Report Share Posted October 1, 2007 OK - a quick self bump - Both ECU and TCM modules removed, contacts cleaned and units replaced. Original ABS unit sent back to Victor for analysis - Meanwhile - the other description I've found for code P1618 is: " the TCM has kindly asked the ECU to turn on the CEL because it has detected a fault in the transmission and can't turn it on by itself"or something like that. So - is this an alternate diagnosis or can one fault code mean 2 different things? One would hope that with all the numbers available they could spread things out and not have to double up... On the off-chance that this may still be a cable problem I'm asking (again) - does anyone have a wiring diagram of the connector(s) between ECU, TCM, and ABS? I know it was on this forum (or as a maintenance question) abou 3 years ago.... anybody? Link to comment Share on other sites More sharing options...
evilb Posted October 1, 2007 Report Share Posted October 1, 2007 What's the year/model and transmission of your car? Link to comment Share on other sites More sharing options...
Tripp Mcnealy Posted October 1, 2007 Report Share Posted October 1, 2007 not quite sure, but i do know that if the abs is still acting up it will throw tranny codes.. "safe mode" and changes the shifting habits of the car.. i had mine get stuck in 3rd and 4 th gear.. Link to comment Share on other sites More sharing options...
DIASPAR Posted October 2, 2007 Author Report Share Posted October 2, 2007 Car is '99 V70XC auto (have to check tranny & control unit model #s )....110K miles.So far the "usual" ABS symptoms I was getting before (flashing UP arrow, ABS light, other CEL P-codes) have not returned since I replaced the ABS module with a rebuilt one from Victor, but the P1618 code/CEL is solid.Thanks... Link to comment Share on other sites More sharing options...
evilb Posted October 2, 2007 Report Share Posted October 2, 2007 Check your messages... hope the diagrams help somehow. Link to comment Share on other sites More sharing options...
garbergtsi Posted October 2, 2007 Report Share Posted October 2, 2007 have you cleared codes from the TCM and ECM? Link to comment Share on other sites More sharing options...
DIASPAR Posted October 2, 2007 Author Report Share Posted October 2, 2007 Thanks to evilb - the diagrams were exactly what I was looking for....no more wiggling wires in the dark.I've been reading and clearing the CEL and codes with my (generic) OBDII reader - don't know of any (non-dealer) method for clearing TCM codes...is there a way? I'll check these diagrams - maybe there's a "clear" terminal somewhere... Link to comment Share on other sites More sharing options...
MrWinkey Posted October 2, 2007 Report Share Posted October 2, 2007 Victor is very good and should work through this with you if he isn't already? Link to comment Share on other sites More sharing options...
garbergtsi Posted October 3, 2007 Report Share Posted October 3, 2007 there isnt....i have had cars in the past that would not clear that code with a generic scantool, but using a good scantool would clear the codes in the TCM and no more problems... Link to comment Share on other sites More sharing options...
Tripp Mcnealy Posted October 3, 2007 Report Share Posted October 3, 2007 just hit up pep boys or advanced and get them to use one of the expensive ones. Link to comment Share on other sites More sharing options...
JRL Posted February 4, 2012 Report Share Posted February 4, 2012 Resurection of an old post. Has there been any positive new info on this nasty code? Link to comment Share on other sites More sharing options...
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