97 850 GLT Check Engine light on? P0740 & P0734 Codes

mwoslund · Post by **mwoslund** » 09 Jan 2009, 20:21

I am a newbie to this site & can really use some good advice: Yesterday I bought a 97 850 GLT with 110,000 miles on it. I have haven't had this car for more than a day and already the Check Engine Light came on. I bought the car from a private party so no return or warranty.

Here's what happened:
The car was running very smooth then after about 25 minutes of driving the little Red Arrow Light on the dash came on & started blinking, at that time the car sputtered a little & the Check Engine Light came on the Red Arrow was still Blinking so I slowed down and noticed the car wouldn't accelerate . I let it set for 30 minutes, when I started the car the Blinking Red Arrow was gone however the Check Engine Light was still on I drove it home (20 minutes) had no problems except the Check Engine Light stayed on.

I let it sit for another hour & started it again and after about 45 seconds of starting it the Check Engine Light came on and stayed on. I took it around block a couple of times, there was no sputtering and it had great acceleration, engine seems to be running smooth it's just that the Check Engine Light is always on now.

Also I noticed when I first got the car that the fuel tank was a 1/4 full and I think the car hasn't been driven much if at all in the last few months before I purchased it.

Any help would be greatly appreciated!
Thanks,
mwoslund

Post by **wheelsup** » 09 Jan 2009, 20:44

Well if it was me I'd take the car back to the seller and threaten to sue. It is obvious they knew about those problems before and sold you the car after clearing the codes. The blinking tranny light is not good news...

OK I thought you had a 95, for the 97 I think you need a special Volvo tool to pull those codes. To get the generic codes I think Autozone or Advance Auto Parts has an OBDII code reader that will read some of the volvo codes. The port is located under the change station (where you put your quarters vertically) at least in my '95.

Post by **Ozark Lee** » 09 Jan 2009, 22:07

Welcome to MVS mwoslund,

From your description you have a couple of different problems but the truth is in the codes.

The blinking arrow is a transmission fault code. Don't go on full tilt just yet, most of those codes are due to a relatively inexpensive part called the PNP switch. When the arrow is flashing it puts the car into "limp home mode" where it only uses 3rd gear. It feels like you are dragging a couple of bank safes around behind the car as you try to accelerate.

The Check Engine light could be anything but a free scan at your local chain auto parts store will reveal a series of "P" codes. Be sure to get the code numbers and don't let the store tell you you need new oxygen sensors which seem to be their fallback position. Get a list of the code numbers and post them back and we will try to guide you through the appropriate course of action. In the meantime try rowing your shifter from low to park a couple of dozen times and it will help to loosen the grease and clean the contacts on the PNP switch. Driving the car with the Up arrow flashing is, in the popular vernacular, a bad thing.

...Lee

mwoslund · Post by **mwoslund** » 10 Jan 2009, 09:35

Today I went & had OBD Test done which came up with the Codes P0740 & P0734. which I am starting to think is some pretty serious problems.
I have a 97 850 GLT with 110,000 mil on it.
Is there anything I can do to correct the issue I am having? Could it be the PNP switch?

Thanks!!

Post by **MadeInJapan** » 10 Jan 2009, 11:44

Welcome to MVS....we hope you end up staying and becoming a contributing member. The codes you got seem to be part of the shifting problem you might be having with your transmission:
DTC P0734 Incorrect 4th Gear Ratio
DTC P0740 TCC Enable Solenoid Circuit Electrical
I would say that the P0734 issue is a result of the other code so fixing the problem (could be electrical with the solenoid in the transmission) for P0740 will automatically clear up the 4th gear shift. Does this sound even close to what's going on with your car? Please post back and I'll do a bit of research on these codes.
-MIJ

EDIT...just found this:
DTC P0740

Try PNP switch first as it is outside the autobox (try with foot on brake, ratcheting your gear shift a couple of dozen times from P down to L and back up and then clearing your codes to see if the light comes back.

If the codes still come up the torque convertor control solenoid is playing up.

Its inside the tranny so you will need to strip the box. I cannot remember if they have a pan on the bottom, but if so its not that hard a job.

DTC P0734 - Gear ratio monitoring (4th gear) fault.

Generally relates to the following:-

1) If the output shaft signal is unstable there may be a problem with the output shaft sensor circuit.

2) If the engine speed signal is unstable there may be a problem with the Engine Management Unit or its sensors.

3) Gearbox mechanical fault. (TCC as above fault?)

4) Exisiting Engine Management Faults Present.

mwoslund · Post by **mwoslund** » 10 Jan 2009, 13:35

MIJ,
Thanks for all your advice.
I went a head and did as suggested regarding the PNP switch and shifting it from park to low a couple of dozens times. So far I haven't seen any lights light up yet.
I did notice that when the vehicle is out of Traction Control mode that the shifting is much smoother! Should I just keep on running the vehicle out of Traction Control, also is if normal the TRAC OFF light to stay on constantly while driving?
mwoslund

Post by **MadeInJapan** » 10 Jan 2009, 13:47

With TRACS off the light will stay on, so yes, that's normal.
If you are having a TRACS issue, this could be the beginning of your ABS module (yes, the two are part of the same system) going too but luckily we've figured out how to repair these ourselves or send them off for a rebuild without costing us an arm and a leg. Even if ratcheting the gear shift helped, most likely the codes/problem will return. If and when that happens, you're going to need a new PnP switch. The ratcheting cleans the contacts in the PNP and is typically only a temporary "fix."

mwoslund · Post by **mwoslund** » 10 Jan 2009, 16:23

Since I just bought this car I did some searching on Carfax and found it when it was last serviced: I will transcribe off the service report:

10/23/08 mileage 110,162
Service dept: Customer states that the ABS Light & the Traction Control light comes on & will not go off, they scanned (customer) before they cleared the codes and P-0500 was on, they just replace the ABS and Bled the brakes.

03/08/07 mileage 109,997
Service dept: Customer request we download software from TCM, which was replaced @ another dealer. Download cannot be done TCM comes with software.

03/08/07 mileage 109,997
Service dept: Needs Trans Assembly, (customer declined)

Note: the vehicle has been driven very little in the last two years.

I am not sure what the TCM is or Tans Assembly?

I hoping this information will help out in figuring out what is wrong.

Post by **MadeInJapan** » 10 Jan 2009, 16:41

That's the transmission control module- the computer for the transmission. It looks, however, like your ABS was replaced. Let's hope this is the module- I would think so- if so, you're not in need of one.

After a re-read, it looks like the previous owner put in a new ABS module- and the dealer, almost 2 years ago recommended a new transmission...the owner replaced the TCM and wanted information off of the old one? Anyway, the miles between 3/07 and 10/08 only increased a smidgen. If the previous owner drove this car at all, I am almost 100% certain that the car has many more miles on it than what is documented. Is the odometer broken? The car probably never needed a transmission to begin with. Don't know about other issues.

mwoslund · Post by **mwoslund** » 10 Jan 2009, 17:03

according to Carfax the odometer is fine, I am thinking the guy may have replaced an ABS sensor? Is it necessary to bleed the brakes when replacing ABS module? I spoke to the guy before buying it and he said he was replacing ABS something??? and the second time I drove it he was telling me that he had to bleed all 4 brakes when replacing the ABS. I am thinking he might have been confused between the ABS module & the ABS sensor?

Is there a way to fine out if the odometer has been tempered with?