Limp Home ONLY when hot outside (?)

TonyG2160 · Post by **TonyG2160** » 30 May 2012, 15:07

First post, although I've lurked for a while. PLEASE help me brainstorm possibilities here:

2004 V70 2.4
This is our 4th (I think) summer of owning this vehicle. So far EVERY year when the temps get 90 plus degrees the good ole "limp home" problem returns. Parking in the shade helps, as does cracking the windows, windshield shades, etc. so there is a definite heat related problem somewhere. The problem with my research (trust me I've searched

) is that the "limp home" issues are so diverse, It seems that just about anything will cause a "limp home" condition.

What happens:
Get in the car (it's hot as hell). Car starts just fine. Start driving. Within 10 minutes there might be some "electrical clicking" sounds that begin to come from somewhere left of and below the steering wheel. Not sure exactly where from though because its very brief and followed by the flashing of ABS/Brake Failure/Check Engine errors, and then the entire electrical system craps the bed (gauges, AC, windows, radio, etc) and the limping begins. You can stop the car, and usually it will NOT restart immediately. It may take a few tries usually accompanied by the same "electrical clicking" that started everything. Finally it will restart, go back into limp mode (but at least I've rolled the windows down now

) and I can continue the painfully slow limp home. Once cooled for a few hours in the shade, everything will be fine for the remainder until it gets hot again. Oh yeah...pulling the regular OBD2 codes reveals only P0600 (Serial Communication Link), and U0101 (Lost Comm with TCM). I'm not sure of the consistency of these codes with previous years experiences of the same problems, but these are the most recent codes thrown.

Possibilities I've brainstormed so far from gleaning through posts:
ECM overheating (does not seem likely as the ECM does not actually "feel" too very hot.
ABS Module (maybe...only because of the initial brake related errors thrown. No stored codes though)
Ignition switch [per this thread: https://www.matthewsvolvosite.com/forums/viewtopic.php?f=1&t=36551 This possibility seems the most intriguing so far because of the "electrical clicking" sounds coming from the drivers lower left, but what has that got to do with the Brake Failure errors?)

The key factor here that I've not really ever seen as a key component in other threads is the HEAT. Early spring, Fall, and Winter are completely problem free.

Does anyone have any further ideas, experience or advice?

Post by **igel513** » 30 May 2012, 18:19

Is the ECM the box by the PS reservoir? If so, you can vent it. My 03 S60's was not vented.

TonyG2160 · Post by **TonyG2160** » 30 May 2012, 19:59

It's not vented, but I don't think the ECM is the problem. I took the lid off of the box and let the car sit in the sun all day. Same problem. Vehicle goes into limp mode after about 10 minutes. I checked the ECM and it was not too hot. I'd at least say that it was very comfortable to touch.

The more I think about it, the more I suspect something in the vehicle interior. I removed the ignition module mentioned in the above post (the part on the left side of the column) and cleaned the contacts. Can't tell if anything has changed yet or not though because the temp had already cooled off. I'll check tommorow. I can definately "imitate" the problem (kinda) by unplugging and replugging the ignition switch quickly, but I've not yet been able to completely recreate the error condition that causes the limp though.

Post by **jimmy57** » 30 May 2012, 21:21

The CEM is to the left forward under dash. It is the main computer for the car.
First thing to do is to make sure all the connectors are plugged in. The main one has a 10mm head bolt holding it in. disconnect the battery neg cable and then undo the bolt, pull of the connector, spray with WD-40 or similar and push it back in and run the bolt in until it clicks. It has a spring nut and will click to prevent overtightening.
The make sure all the relays are pushed and the black shunt strips are fully seated. Connect battery and then see if that does it.
If not re-post and we'll discuss plan B.

TonyG2160 · Post by **TonyG2160** » 31 May 2012, 20:07

So far I'm unable to verify the success or failure of anything tried so far. I'm really leaning toward the CEM though as that seems to be where the clicking sounds originate from. Once the weather warms back up down here (cold front with highs in the upper 70's) I'll check see if there are any changes.

Post by **coflynn** » 01 Jun 2012, 12:19

Hello,

Jimmy57's advice sounds good to me - many problems are related to bad connections! In addition:

#1. I would first off find someone with a VIDA/DICE to pull actual diagnostic information. You'll be wasting too much time otherwise chasing down possibilities! In addition VIDA would let you individually power on different relays the CEM controls to narrow down possibilities (see #2 below).

#2.

Within 10 minutes there might be some "electrical clicking" sounds that begin to come from somewhere left of and below the steering wheel

As in a relay clicking? Does this happen when driving normally (e.g.: after 10 mins in cooler weather)? I would narrow down what is being turned on, and probably that system has an issue. Car is turning on AC, switching modes, etc.

I somewhat doubt anything directly related to the transmission is overheating, only because the problem so specifically starts when you hear that clicking, and not when the car has already been baking in the sun. I suspect the heat is indirectly causing the problem e.g.: car is turning on some system because of the heat, OR is turning on something else which is already overheated, which then causes the problem. By causing the problem, I mean it is disrupting the comm links connecting different modules. This would cause tons of problems in a car, and I would basically ignore what 'specific' lights are being lit. It will probably light everything that it doesn't know with 100% certainty is OK.

As an example from VIDA here is some info on two relays the CEM controls of interest (there is a lot more though, but these are two which could be switched):

*the status of the relay for extended X supply. The relay controls the power supply for the following functions: parking heater, power driver's seat and “after blow” for the air conditioning (A/C) system. The relay is activated in key positions I, II and III when the drivers door is opened (10 minutes), driver's door is closed and key position 0 (1 minute) and when one of the above functions is activated

*the status of the relay for extended X2 supply (AUT). Controls the power supply to the gear selector module (GSM). The relay is activated in key positions I, II, III, 0 or out for 10 seconds

Post by **jimmy57** » 01 Jun 2012, 12:32

VIDA is going to be FULL of codes.
IF you get a scan with a qualified tool then look for DF code(s) set by CEM. Then 1A codes set by CEM.
There will be a load of -001 and -003 codes present when the car is functioning.
The clicking relays is more common with CEM internal faults......

casto9 · Post by **casto9** » 21 Jun 2012, 18:01

Any update? My 2004 XC70 has done the exact same thing. First happened on an extremely hot day last Fall. When I got it to the dealership, they couldn't figure anything out. Didn't happen again until this past week when the temp got into the mid/upper 90's. Although, it doesn't get hot enough here frequent enough to be a serious issue, it is annoying.

Post by **igel513** » 05 Jul 2012, 19:52

TonyG, any update?

louphi · Post by **louphi** » 20 Jul 2012, 13:27

2004 Volvo XC70, 100,000 miles. Providence RI.
My daughter is experiencing the same problem. Limp mode, multiple code errors ranging from rear door open to ABS/ airbag failure, red triangle warning signal. Have taken to local dealer several times and they can't get to it for 3 days and no codes except "stem failure" remain. Once they get around to examining the problem and driving it for 30+ miles they can't recreate the problem. Only code is as above. They say they can replace the part but no guarantee's and they also had no idea what alternative problems could be causing this -- which is amazing for a mechanic to say. Their quote " replacing this part would be a shot in the dark". Is there some recall issue here. We're at wits end. Advice or follow-up from your experience is greatly appreciated