Got check engine light and flashing up arrow. Mechanic pulled code and says it's DTC 76 in TCM, "permanent failure", there was no other code he said, and he could not clear the 76 code.

Made an appointment w/ a tranny shop in town for next week but am impatient to know what this all means.

I drove it 15 minutes after that and the flashing arrow stopped, and now I just have CEL.

Any thoughts?

Thanks.

 

Dunno what kind of scanner your mechanic used and whether it can properly read transmission fault codes from a Volvo. What I'd do is have the CEL codes scanned via an OBD2 code reader (you can borrow from Autozone etc) then write it down and clear again. Also, when I've had odd shifting in my S40, I've resorted to doing a shifter row to clean the contacts on the PNP switch (ie go park to lo to park 20x fast) and the bad behavior has always gone away. The other thing to do is to have your shop check for transmission fluid leaks and check the fluid level and fluid color/smell (there's a correct procedure for measuring both cold and warm levels )

 

Just a generic question for the OP - what is the history of transmission fluid changes on the vehicle?

 

Not certain. Bought used recently.

Took it into a local transmission shop today and they said the code disappeared and would not come back on. They said this is weird. Suggested waiting until it comes back on.

The seller told me it had the P0700 and P0705 code before (but the codes turned off), so I'm guess that's what this has. And based on everything I've read it's the PNP device?

I guess I'll wait for it to turn back on.

 

I read somewhere that the DTC 76 refers to the fact that the check engine light was set to on. Not sure if that's true, but its not a standard OBD2 code. The P0700 is a somewhat generic fault code - most fix it sources say to inspect wiring and check fluid level. P0705 says there's a fault with the gear selection input to the TCU - thus the reference to a wonky PNP switch. One of the key things is to pay attention to other symptoms - Do you have hard shifting or signs of slipping? Does the car behave different when cold or hot (say after a long drive) etc. Did the tranny shop confirm good fluid quality and quantity?

 

Helpful info. Thank you.

When warm/hot, the shifting is smooth. When cold, I can feel it shift a little bit, but I wouldn't call it hard shifting.

My regular mechanic said tranny fluid was at a good level, but didn't mention quality.

Thanks.

 

With an unknown service history on that transmission, I'd recommend doing a drain-and-fill. I'm not familiar with your specific model, but it's generally easier than an oil change (no filter - just drain and pour in new fluid). Modern transmissions are very sensitive to fluid quality, and the amount of wear the tranny experiences has a lot to do with how clean that fluid is. It's cheap and easy, and the best insurance you'll ever buy, dollar for dollar.

One thing I'll say is that I'm jealous of your car if it's even possible to test the transmission fluid level. Volvo's crack engineers made it virtually impossible to do it on the 2005+ models.

 

Well... the flashing arrow and the CEL came back on just before I had to drive to a city 2 hours away.

I noticed on my return trip that ... (a) the transmission shifted roughly when I went from Park to Drive; and (b) it drove sluggishly. By that I mean, when starting from a stop, it was slow to accelerate, like it was trying to start in second gear; AND when I was cruising on the freeway at about 60 mph, it was revving at about 2800 RPM, which seemed high. After I stopped for gas, the car felt normal again, with smooth shifting into Drive, responsive acceleration, and needing only about 2100 RPM to cruise at 60mph -- even though the whole time the arrow was still flashing and the CEL was still on.

When I got back to my home town, I had the CEL codes read at an Autozone, and the printout gave p0700, p0705 AND it said to replace the stoplight switch (no code associated with that, at least not in the Autozone report). I'm guessing that the stoplight switch issue is completely unrelated to the transmission problem. In fact, cruise control was not working on this trip -- so I'm guessing the brake light sensor is stuck in the "on" position.

Does the hard shifting, sluggish acceleration, and high-RPM cruising sound like it might be caused by a bad PNP switch?

Thank you.

 

If your PNP is acting up then you could get incorrect gear selection. Also check to make sure your winter mode is not engaging which will force the car to start in 3rd gear. How does the car behave when you manually shift gears - ie start out which shifter in low, then manually up shift through to D? Also try doing a "shifter row" (turn key to position 2, and then move shifter from P to lo to P about 10 to 20 times fast). This can clean up the contacts in the PNP and can help clear the problem in some cases. Hard shifting can be a sign of issues within the tranny - you may want to consider a fluid drain/fill. Start with a paper towel test - pull the transmission dipstick out to check fluid level cold, wipe on a white paper towel to check color. Should be reddish brown or brownish. See if it smells burnt. Black is bad... then drive car through a full 15 minute cycle to fully warm transmission. Check transmission level again (dip stick should have both cold/warm fill lines). If it seems way off,consider a visit to your local mechanic for an inspection for leaks etc. If its dark, consider a drain/fill - just make sure to check the owners manual for the correct fluid for your model (I believe the 5 speeds use JWS3309 and the 4 speed autos use Mercon/Dex III so you need to verify).

 

Great tips! Will try/verify one by one and report back.

 

Welp... I'm back.

My 2003 s40 had its check engine light on, with code p0700 and p0705. It would periodically flash the arrow in the dash, and go into limp mode. So I had one mechanic replace the PNP switch. He said the car drives fine now but he could not make the CEL stay off. He'd clear it and it'd come right back on when he restarted the car.

I took it to another independent garage, and they said since the PNP switch was replaced, there must be something wrong w/ the TCM, and said I have to take it to the dealer. They said the TCM is throwing code 76.

The dealer says they'll charge $150/hour to diagnose.

Other than CEL staying on, the car drives fine now. The oil is light/reddish brown, and the level is good with engine on and off.

Any ideas on what I can try ... other than going to the dealer?

Thanks!!

p.s. At one point I took it into AutoZone to have the CEL code read. It read the same codes, p0700 and p0705, but their printout said it could also be due to the brake pedal sensor. I wonder if that's true -- last I drove it on the freeway, cruise control would sometimes not work. But nobody else other than AutoZone says p0705 is due to the brake pedal sensor, so I'm not sure about this.

 

interesting about the brake pedal sensor - that is wired into the cruise control so maybe its a hair off and needs adjusting. Worst case is you replace that and you fix your cruise control :-) I also read an old post where somebody reported their 0705 code was caused by a sticky shifter W button... The only other cause I can think of is in the wiring to the PNP - ie a dirty pin causing a faulty signal.

 

OP here. I took my to an independent Volvo specialist 1.5 hours away, and they cleared the code in the TCM and in the ECM, and the CEL went off. I should have gone to them in the first place!