1999 s70 in limp mode

cjiwash · Post by **cjiwash** » 14 Sep 2021, 19:08

Hi there -

New to this forum and would like some feedback on this car. Have been struggling with finding out why it is stuck in limp mode. Replaced spark plugs, changed the transmission oil (stays in 3rd gear, trans oil and filter replaced). Also checked exhaust system for blockage. The engine does not rev past 3500 and car is stuck in 3rd gear from the get go.

I have no check engine light on, yet it is in limp mode. Could this be the ECM because it is not recognizing the limp mode and turning on the CEL?

If so can it be replaced without it being programmed to the specific vehicle? Is a used one worth the effort?

I was thinking it could be the ETM, however won't that activate the CEL?

Thank you for anyone's help on this -

Calvin

Post by **scot850** » 14 Sep 2021, 19:30

Welcome to MVS!

So let me understand what you are seeing. There are no dash warning lights on in the cluster at all?

Was the car running fine before you changed the plugs, or did you change the plugs and the problem then happen?

If the latter option, then it is something that got disturbed or not put back when installing the plugs.

It is unusual for a code not to get thrown.

Does the transmission show an upward orange arrow in the dash cluster about the middle bottom of it?

Turbo or non-turbo?

If the spark plug change was to try to fix the limp mode issue did the car show any issues prior to this?

Neil.

cjiwash · Post by **cjiwash** » 15 Sep 2021, 05:17

Hi. Thank you for replying!
There are no lights on the dash, including the CEL. That’s why I kind of suspect the ECM because it is not seeing the engine in limp mode. But not sure.

The car was in limp mode already when I changed the plugs, and checked the exhaust. Since it was stuck in 3rd, I changed the trans oil thinking it may help. Trans oil was very dirty.

The orange arrow did not appear, only appears when I push the button on the shifter. This is non turbo

Post by **scot850** » 15 Sep 2021, 11:12

While it is possible it is the ECM, there is a possibility the ECU and TCU have corroded connectors. I had issues with a V70 and it was the opposite that it had loads of dash lights on. It was fixed by removing the ECU and TCU units and carefully cleaning the contacts and then reseating and removing the units 2 or 3 times to help make sure the contacts are clean.

The ECM/ETM is a known problem issue with these units. Talking to someone like Xemodex may help you to identify if the ECM is bad and needs re-built.

Neil.

cjiwash · Post by **cjiwash** » 15 Sep 2021, 15:19

Thank you Neil. I will definitely check this out. Appreciate it

Calvin

Post by **scot850** » 15 Sep 2021, 16:15

Good luck with this! If you can get any codes out of this, be aware some generic testers cannot read the codes. It may be worth taking to a dealer if possible to have them read the error codes.

The longer route is to by a Vida-Dice unit from China and the software to connect to the OBDII outlet to read the codes yourself. The system can be a little difficult to set up on the computer, but there is a separate section specifically for that. Our good friend on here, Rick I believe has even managed to get it running on newer than Win7 (Win10?) and write a patch for the date expiry code for which we are all really grateful for.

Just so you know, I am currently having random issues with my car (00 V70R) around dash-lights and running issues. Still not sure what the route cause is but have suspicions!

Let us know how you get on.

Neil.

cjiwash · Post by **cjiwash** » 16 Sep 2021, 00:37

Well, today I removed both ECU and TCU units and cleaned the terminals, and worked it in and out to secure the connection.

Car still stuck in 3rd gear and still in limp mode. Will not rev past 3500RPM. Car runs smoothly at idle, and still no check engine lights .

Puzzling.

Post by **abscate** » 16 Sep 2021, 05:08

You need to get the car connected to VIDA and confirm the throttle position sensors are reporting the same values. Probably, the ETM is failing although usually you get the ETS light lit on the dash ( confirm that the light is working on key position II, of course )

You can’t diagnosis electronic cars by symptom today, and 1999 was the beginning of the end of the symptom era for Volvo

Post by **scot850** » 16 Sep 2021, 10:29

I agree with abscate. You have got to the point where you now need diagnostic help. Otherwise you are in the expensive position of throwing parts at it. It is most likely a failing ETM throttle unit. That is where a call to Xemodex should be considered as they might be able to help you diagnose the symptoms.

Neil.

cjiwash · Post by **cjiwash** » 16 Sep 2021, 14:38

Thank you for all of your assistance. If it is the ETM, does it need to be programmed to the vehicle by the dealer before installation? I have been hearing yes and no.