98 S70 Strange Transmission issues Topic is solved

yanga001 · Post by **yanga001** » 03 May 2020, 13:20

Hi Everyone,

So i picked up a 98 s70 N/A a while back for parts and it seemed that the only issue with it was a bad transmission. After taking a look and doing a drain and fill i seem to be getting a P0748 and the flashing up arrow of death. Well, we checked the PNP and it seemed fine. There was no indication of damage or chips after doing the drain and fill, and it seemed to have all the pickup when going in reverse.

After leaving it for a bit i found some more time due to the pandemic and tried to take it out down the property to see if it felt dead. I had no pickup in drive as was expected, however dropping it into L & 3 resulted in the car operating and shifting normally through those gears. There were no lurches or any indication that the transmission was dead.

Given all this my best course of action seems to be to pop out the transmission and take a look at the S1 shift solenoid.

If the shift solenoid was bad, would the car still be able to shift normally in L and 3 gears? Reverse also works fine. An unrelated issue also include hard hot starts to the extent that the car will run normally and not start after when it is hot. Letting it sit for a while seems to do the trick. Im pretty sure its a fuel pressure related issue and not related to the transmission.

Thanks!

Post by **RickHaleParker** » 03 May 2020, 14:15

There still hope for that transmission.

P0748 does not translate to a 1998 S70. I think you OBD scanner has poor translations. Not uncommon for generic scanners. I suggest you get a ELM327 interface version 1.4 or higher (or a good quality clone) and scan it with 850 OBD-II.

P0748 is a generic code for Pressure Control Solenoid. Could be as simple as dirty connectors or wiring defects.

Post by **Ocelot** » 06 May 2020, 04:53

RickHaleParker wrote: ↑03 May 2020, 14:15 There still hope for that transmission.

P0748 does not translate to a 1998 S70. I think you OBD scanner has poor translations. Not uncommon for generic scanners. I suggest you get a ELM327 interface version 1.4 or higher (or a good quality clone) and scan it with 850 OBD-II.

P0748 is a generic code for Pressure Control Solenoid. Could be as simple as dirty connectors or wiring defects.

Does this scanner in combination with the mentioned app also work on my Volvo S70 with the Feniks 5.2 motormanagement?

yanga001 · Post by **yanga001** » 06 May 2020, 12:46

Update: I seemed to have lost my cheap vag/com cable for Volvo-FCR so cant scan it with that till i find another one. I have a good ELM327 but its usb so ill need to find an otg cable for the App. I know VolFCR covers Feniks 5.2 but you need the correct Vag/Com cable with the ft232 FTDI from what i heard. You might be able to use the CH340 if you can port it as a serial port and then import that into a virtual machine although i have not tested it and would just buy the correct cable.

Ill take a look at the cables this weekend.

yanga001 · Post by **yanga001** » 18 May 2020, 15:07

Update & Conclusion:

So going off the fact that the OBD2 code was wrong i had decided to try a few more random solutions for the car. I popped open the TCM and ECU housing and found that the car was running a Jetronic 4.2 (serial number 5?) and the normal Aisin TCM. I swapped the TCM & ECU with a working one from the wrecked v70 and the flashing arrow of death is now gone!! I was quite surprised by this as i was so sure there was something wrong with the transmission given that its done 300,000km + and was a bargain price at $300. The car still has a rough idle which i am pretty sure is due to a bad fuel pump and some old plugs.

Anyways, the Transmission issue was resolved by replacing the TCM with a known working one. The ECU swap was just for fun.

Post by **scot850** » 18 May 2020, 15:26

Well that was a great bit of luck! Hopefully the rest is down to a good tune up, new gasoline and a good run to blow the cobwebs out!

Neil.

Post by **RickHaleParker** » 19 May 2020, 16:15

yanga001 wrote: ↑18 May 2020, 15:07 Anyways, the Transmission issue was resolved by replacing the TCM with a known working one. The ECU swap was just for fun.

Was the connector dirty ? Keep telling people that you got to maintain the electrical wiring and connectors on the microcomputer controlled cars. Probably sound like a parrot to some. One cannot let the electrical wiring and connectors go like one could on the old electrical/mechanical controlled cars.

Last week my S40 was misfiring. Cleaning the connector to the MAF was all it took to make it fly right. It is a first generation on the X40 platform. It has a waste spark ignition system.

Post by **misha** » 20 May 2020, 13:17

All '97 & 98 20v cars B5254S have Motronic 4.4 management...not Jetronic and certainly not Jetronic 4.2.
LH 3.2 Jetronic is used in early 850 with separate ecu(s) for engine and ignition.
Jetronic 4.2 doesn't exist in these cars.

Post by **misha** » 20 May 2020, 13:41

yanga001 wrote: ↑06 May 2020, 12:46 ...I know VolFCR covers Feniks 5.2 but you need the correct Vag/Com cable with the ft232 FTDI from what i heard...

Vol-Fcr doesn't cover Fenix 5.2 and M4.3. since they are OBDI and still produce flash codes.
It covers just M4.4 management which is fully OBDII.

yanga001 · Post by **yanga001** » 21 May 2020, 13:42

misha wrote: ↑20 May 2020, 13:41
yanga001 wrote: ↑06 May 2020, 12:46 ...I know VolFCR covers Feniks 5.2 but you need the correct Vag/Com cable with the ft232 FTDI from what i heard...
Vol-Fcr doesn't cover Fenix 5.2 and M4.3. since they are OBDI and still produce flash codes.
It covers just M4.4 management which is fully OBDII.

My bad, thanks for the corection.