Sudden codes and pour drivability!

heatdev · Post by **heatdev** » 17 Aug 2020, 12:32

Hello Folks,

2000 v70xc... Never had an issue with this Volvo. The car is angry.

The car had a tune up last fall while I was on a road trip. NGK BKR6EGP G-Power plugs were installed oil change, and trans fluids.

The car ran fine for a 300+ mile trip home before it sat for six months due to the pandemic. I've put under 7k since the service.

Drove it to get new tires, and I can't explain to you how poorly the car is running. It's misfiring, hesitating, stalling out, back fireing, CEL and service lights are on... car has has no power, and I'm getting 6.4 mpg in mixed driving, with a fair bit of highway time.

I know needs plugs, but I have the following codes for the first time ever:

4 codes:

P0722 VOLVO Faulty Speed Sensor Speed Sensor harness is open or shorted Speed Sensor circuit poor electrical connection

P1618 VOLVO Engine Control Module (ECM) to Transmission Control Module (TCM) harness is open or shorted Engine Control Module (ECM) to Transmission Control Module (TCM) circuit poor electrical connection

P1550 speed signal abs

P301 Misfire cylinder 1

The car has been 100%, prior to this.

Any and all advise welcomed, thanks!

gd

Post by **June** » 17 Aug 2020, 13:01

Low battery, but still strong enough to start fine will piss the computer off on these. It has sat for 6 months so if the voltage is slightly low??? Could water have intruded somewhere? A varmint chewed th wires under the hood? Bad gas from sitting? I know my 04 S80 gets real funky when the battery is on it's way out. June

heatdev · Post by **heatdev** » 17 Aug 2020, 13:09

All good points! Battery was at 4 volts. Used battery charger to get it back to 12+ volts.

I put in a half a tank of fresh gas, with injector cleaner in the tank, and a few ounces of seafoam in the crankcase. Thanks for input, it's much appreciated. Time to get back under the hood.

Post by **FlyingVolvo** » 17 Aug 2020, 13:51

Low battery will cause weird stuff to happen, though I'm not sure that's not your only issue. I would fully charge battery, disconnect it for a while, then start from scratch. See what codes show up if they show up again after a clean slate.

Most of what you describe just sounds like a misfire (and you have a code for it). Suspects for that would be a bad coil, bad plug, or possible stuck fuel injector. If it were me, I'd change the plugs to OEM or Bosch coppers. These cars are sometimes know to have issues with Platinum and non-OEM spark plugs. If you still get misfire, swap the #1 and #2 coils and see if error transfers. If so, bad coil. If it's good, swap #1 and #2 fuel injectors. Same logic as above.

If the ABS/speed sensor stuff shows up again, that is most likely the ABS module itself. Don't pay for a new one, there are many places online (and some members here I believe) that can rebuild ABS modules for a fraction of the cost of a new one. This is a pretty common failure.

Also... when things are feeling that off and whack, stop driving it! Usually stuff like that doesn't just sort itself out by itself, and driving while misfiring can possibly do damage to other components. I'd keep it to your neighborhood street just for drive testing.

heatdev · Post by **heatdev** » 17 Aug 2020, 14:01

Thanks for the reply, sound advice. I swapped the coils as you suggest, and no change. I'll try pulling the battery for a while... It's fully charged, and charging now.

I'll get on testing the injectors. The speed senor.. associated with the trans. I've been looking for it under the hood with no luck.

Thanks again,

gd

Post by **FLXC90** » 17 Aug 2020, 17:16

Speed sensor is in the wheel hub. Behind the brake disc. Held in by a 10mm head bolt. Could be dirty, but as Ed says, most likely culprit is ABS module. Or as June asked, "Got Mice?" Pull the connector from #1 injector and check for corrosion, reseat it and see if it helps. If you can pull the injector and test spray pattern, that is best. As was said, swap the 1 and 2 injectors. (Not just the connectors, that would be a bad misfire situation) see if the issue moves. Could be a dirty or clogged injector.

Post by **FLXC90** » 17 Aug 2020, 17:22

Also, if you have the tool, while the battery is out, pull your ECU and TCU, clean connectors with De-ox it or other terminal cleaner, see if that helps with that code.

heatdev · Post by **heatdev** » 17 Aug 2020, 17:52

Thanks for the information. I will check the sensor at wheel as well. The sensor I was referring to is the transmission speed sensor/rpm sensor…I suspected due to the ECM PCM errors, and now I've discovered my Speedo falls off, but doesn't quite go into limp mode... Maybe because it's already there.

I reconnected the battery after some time, and drove the car 5 blocks and rescanned and received the following readings:

I unplug the battery for a couple of hours

No Service Light
No CEL
TRACS and ABS are on
These are the codes

P0301 misfire cylinder 1
P0722 speed sensor
P0171 vaccum leak
P01238 Turbocharger Control valve
P1618 ECM TCM Error.
I will inspect the vaccum lines tomorrow
Along with the sensors at the wheels, and at the transmission. Check the MAF, injectors.

I'm totally unaware of what tool I need to access the ECU, and TCU, never been in there.
No time like the present to learn!

Thanks for the tips, and knowledge. I'm learning.

Cheers,
gd

Post by **FLXC90** » 17 Aug 2020, 18:19

D'oh OK speed sensor signal would be sent to ABS module, sends to cluster, check module and wiring connector at module. Also could be the TCM wiring fault. Also, try rowing to clean PNP switch (search Forum)

heatdev · Post by **heatdev** » 17 Aug 2020, 18:41

Thank you. I did the row yesterday after getting the car home. It's shifting much better. Trans flush may be in order. Hopefully the list gets smaller. Cars due for inspection. I'm almost 90% sure the abs module is toast. But I'm going to keep digging until everything is sorted.

Thanks for the help!

gd