[Eric Beatty]

Hello everyone. I'm brand new to this community/forum. The subject line above summarizes my situation but here's a more expansive description.

My daughter's 2004 S60 2.5T with automatic transmission went into Limp Mode a couple of weeks ago and became virtually undrivable. It starts up just fine and idles normally BUT it will not rev above 1Krpm when placed into Drive. It won't go above 8-10 mph on level ground and is absolutely incapable of climbing the slight incline in our driveway.

We've had this car for nearly 8 years now and this is the first time that we've ever had any issues with it. All work on it has been strictly maintenance/upkeep - oil/fluid changes, brakes, etc. Never anything performance or operability related. Hence, Ic diagnostic tools don't own/have any Volvo-specific diagnostic tools like the VIDA system that I see mention a lot online. All I have is a simple OBDII scanner to read codes.

Anyhow, when the "Reduced Engine Performance" message appeared in the little window at the lower left corner of the dash, it was NOT accompanied by any CELsymbol lighting up on the dash.

Nevertheless, I used my OBDII scanner to read the car and got 4 codes: P2121, P2122, P2121pd, and P2122pd.

Looking those up online pointed me to several communities (including this one) that indicated that the engine throttle body or the accelerator pedal assy with buit-in position sensor were the likely culprits.

I have replaced both of those - first the throttle body assy - then the pedal assembly - with no change in results.

I have also read that the wiring/connectors for these units can be susceptible to corrosion so I made certain to thoroughly clean the connectors with CRC Electrical Contact Cleaner when disassembling and reassembling things. Further, I purchased an ECU removal tool and carefully unseated the computers, carefully cleaned the connectors and sockets, and then reassembled them.

Again, still nothing changed. At this point, I am absolutely stymied. I am posting this in order to seek far more knowledgeable help. Is there anything that I potentially missed or overlooked?

I ALWAYS made sure to perform all the electrical/electronic component replacements, cleaning, etc. with the battery fully disconnected. Is there any procedure that I might have not known about to reset the ECU and clear out the "Reduced Engine Performance" message? Will not clearing that message from the computer prevent the system from operating correctly, even with the new parts installed?

I'm hoping beyond hope that you folks can guide me to the solution. Once again, the P2121 and P2122 codes are the ONLY codes that the car is generating (as far as I can tell from my simple OBDII scanner).

Thanks in advance for any tips, sugestions, theories, ideas, etc. that you can share with me.

Cheers,
Eric

 

[Phixion]

Hello Eric and welcome to Swedespeed! I have a 2004 2.5T FWD myself and over the past several years gotten a random P2127 code that'll pop up and basically makes my accelerator inoperable, won't rev the car or anything. Generally turning off the car, cleaning the code and starting back up will make it like nothing ever happened. Usually this issue rears its head when I'm stopped at a light, then it turns green and I hit the had and nothing! Just the slow creep you get when it's in gear and no throttle input. It's happened once while on the freeway going 70 mph when I let off the throttle momentarily since years ago. Have yet to replace anything or figure out why it's happening.

In any event, I'm assuming you've already tried clearing/erasing the codes and that doesn't help. Next question, how's your battery? Sometimes a bad or low battery (low battery health, not low charge) can cause wonky electrical issues. If your battery is good, try the electrical reset procedure. Remove both battery cables from the battery, hold them together for at least 15 minutes to help discharge any transient electricity in the car. Then reconnect them to the battery and see if things go back to normal. This process has solved many owners lingering electric issues.

Next I'd check fuses. There's multiple fuse trays, one under the hood, one in the side of the dash on the driver's side, one at the CEM module under the dash and then one in the trunk at the REM module on the driver's side behind the panel that folds down. I unfortunately don't have all the fuse designations on me at the moment, but perhaps @volvogod who's affluent in the electrical system among other aspects of our cars might know exactly what fuses to check. Other than that, I'm not sure what else to check. I think if I recall I've heard of the wire loom that runs from the throttle body connector back to the ECU can sometimes go bad, but I'm not sure of the symptoms of that.

 

[Eric Beatty]

Thank you for your reply. I haven't seen the P2127 code at all. Only the P2121 and P2122 codes. I've cleared my codes several times and each restart only serves to bring them back within mments.

My battery is strong and I have NOT tried disconnecting ther battery in the manner that you described. But, I will do that this afternoon. I will also examine the fuses. I did see in another post somewhere that fuse #8 in the underhood box controls the throttle/pedal assembly. I will check that also this afternoon.

 

[Phixion]

You're welcome! In your case since resetting the codes it'll immediately return, that to me indicates a definite issue and not a fluke like I experience with my P2127 code which is very random and intermittent. That's good your battery is strong, we can rule that out then.

 

[Eric Beatty]

I checked my fuses and discovered that slot #8 fuse is the one that controls the throttle pedal sensor and the AC clutch. AND it was blown! So I immediately replaced it and started the car but nothing had changed.

So, I took a look at that fuse again and discovered that the replacement I had just installed 5 minutes earlier was also blown. I found another 10A replacement and repeated the process. Yep, that fuse also blew! Having now exhausted my supply of 10A fuses, I ordered some more from Amazon (they're out for delivery right now) and did some additional Google-ing. Once it is lighter out, I'm going to disconnect the wiring connector to the A/C compressor clutch and try replacing the fuse yet again to see if it continues to blow. Wish me luck! 🤞😀🤞


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[Horsehockey]

Sounds like the fuses are fine. Time to track down the short circuit.

 

[Eric Beatty]

Sounds like the fuses are fine. Time to track down the short circuit.

I've now found lots of references to the A/C clutch causing these shorts, hence my starting there.

 

[Phixion]

If it keeps blowing, there's something wrong with the A/C clutch and/or compressor unit or perhaps a relay to the system. But at least you do know the cause of the accelerator issue.

 

[Eric Beatty]

UPDATE! Problem solved!

I removed the FMI1 relay for the A/C, replaced the 10A fuse in the #8 position of the underhood fuse box and everything was normal again. Now, my next task is to track down the short in the A/C compressor/clutch wiring. Luckily, here in the Pacific NW, I won't be needing A/C until some time in late July or August and then only for a few weeks at most. 🤣

Nevertheless, I'm not going to wait that long on it. Thank you again to everyone who contributed to my finding the (interim) solution!

 

[Phixion]

This is great to hear that you got your car drivable again until you can resolve the A/C issue.