Limp mode, rough idle, multiple ECM codes - need help

krenekj · Post by **krenekj** » 06 Jun 2024, 16:17

2002 V70 non-turbo
217k

Last week, the car started having a rough idle, stayed in first gear and the max speed was about 20mph (limp mode I believe). Turning it off, and letting it rest for a few minutes sometimes returned the car to normal behavior, so it's intermittent.

Because the codes pointed at the ETM and XeMODex rebuilt the ETM 7 years ago, I shipped the ETM to them earlier this week and they found 'faults' with it. They sent a replacement unit and I installed it today.

Unfortunately, the SAME symptoms and codes appeared within 10 miles of running the new replacement unit from XeMODex. The ETM connection at the wire harness is clean and solid.

What should I be checking (and how) besides the ETM?

Codes:
- P1026 - clutch speed comparison
- ECM - 914F throttle unit, internal fault, faulty signal
- ECM - 980F engine control module (ECM) faulty signal
- ECM - 91 F0 throttle unit, internal fault, faulty signal
- ECM - 91 A7 throttle unit, internal fault, faulty signal
- ECM - 903F throttle unit, internal fault, faulty signal

Message in the lower left display: Engine System Service Urgent

Thanks in advance!

Post by **jonesg** » 06 Jun 2024, 19:39

krenekj wrote: ↑06 Jun 2024, 16:17 2002 V70 non-turbo
217k

Last week, the car started having a rough idle, stayed in first gear and the max speed was about 20mph (limp mode I believe). Turning it off, and letting it rest for a few minutes sometimes returned the car to normal behavior.

Because the codes pointed at the ETM and XeMODex rebuilt the ETM 7 years ago, I contacted them to initiate a warranty claim. I shipped the ETM to them and they found 'faults' with it, so I received a replacement unit and installed it today. After a nice start to a test drive, the SAME symptoms and codes appeared within 10 miles.

The ETM connection at the wire harness is clean and solid.

What should I be checking (and how) besides the ETM?

Symptom: rough idle, stays in first gear, max speed about 20mph (limp mode I believe). Turning the car off, and letting it 'rest' for a few minutes sometimes returns it to normal behavior, so this is intermittent

Message in the lower left display: Engine System Service Urgent

Codes:
- P1026 - clutch speed comparison
- ECM - 914F throttle unit, internal fault, faulty signal
- ECM - 980F engine control module (ECM) faulty signal
- ECM - 91 F0 throttle unit, internal fault, faulty signal
- ECM - 91 A7 throttle unit, internal fault, faulty signal
- ECM - 903F throttle unit, internal fault, faulty signal

Thanks in advance!

what are the codes now with th new etm.

krenekj · Post by **krenekj** » 06 Jun 2024, 21:25

The codes are the same as with the first ETM.

Post by **jonesg** » 07 Jun 2024, 03:43

cable problems are not rare with these.
some dealerships change the plug and harness to prevent come backs.

krenekj · Post by **krenekj** » 08 Jun 2024, 09:58

Update:

We drove the car home last night in limp mode - it was left in a nearby neighborhood to wait for a less busy time to crawl home. Going downhill it shifted gears and got some good speed (40mph!), but going uphill was a real struggle.

Here are some additional things that have been done to find the issue:
- cleaned the wire harness plugs - it looked clean already, but having a 240 as well, I know that looks are deceiving.

- performed a fuse #7 test. With the ignition 'on' and the engine not turning over, I pulled fuse #7 and reinserted it. Nothing happened. No clicking, no buzzing from the ETM - nothing.

- traded emails with XeMODex yesterday and they've said to get the car checked by a Volvo indy mechanic. I'm scheduled to bring it to my local shop Monday.

I'd like to continue debugging this weekend. I no longer have access to VIDA.

Are there specific instructions for testing the connections the ETM plugs into? Checking connectivity for the 6 wires would be terrific, but I don't know where the wires go or terminate. Any pointers?

Thanks

Post by **jonesg** » 08 Jun 2024, 16:03

i would start with the wiring diagram.
considering a genuine volvo harness only costs $46...

https://www.fcpeuro.com/products/volvo- ... wE#fitment

krenekj · Post by **krenekj** » 08 Jun 2024, 16:19

Any pointers to the wiring diagrams? Also, I've tried to trace the other end of the ETM wiring harness but cannot find it. Where does it terminate? I can then test continuity across the harness to see if I need a new one.

Post by **jonesg** » 08 Jun 2024, 17:13

well i'd say it has to terminate at the ecm.
I'd disconnect battery , pull the ecm and probe the terminal block to check wiring integrity to etm.
or disconnect the battery and use piercing probes to check the wires under the computer box.

I have a prescription to ALLDATA DIY, not the professional version but ok.
I also have vida, I don't know if vida includes wiring diagrams but ALLDATA does.

Volvo V70 (2002) Wiring Diagrams from google..

https://www.google.com/url?sa=i&url=htt ... HQAAAAAQBA

if you want, pull the ecm and inspect socket for green gremlins.

dikidera · Post by **dikidera** » 09 Jun 2024, 07:12

Also clean the holes with a contact spray.

krenekj · Post by **krenekj** » 17 Jun 2024, 21:41

Quick update.

I left the car with my local indie shop while I'm out of town. They used VIDA to test the ETM, which would not respond to various commands. They swapped in a spare ETM they had on the shelf, which responded correctly for all tests. All indications are the ETM is faulty. XeMODex is hesitant to provide another ETM in case there's an electrical problem that would cook the ETM.

So I'm considering sourcing an ETM (part number 8644344 or 36001821) to try it. Thoughts?

Any other ideas?