That does seem unusual. Mine has none right there and I have no idea why they're not connected to anything.

I had to get a new pedal when I started getting codes for that. I have no idea why as I tore apart the internals and it all looked perfect, with little to no wearing on the resistance tracks inside.

 

I have made a discovery. The accelerator pedal reports to two systems for redundancy.

1 system is good and is controlling throttle.

The second one is not receiving info so it’s throwing car into limp mode.

I feel like I need the connector and the proper pin-outs for the accelerator.


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Maybe this is of help

View attachment TP3978202 S40 V50 2004 Wiring Diagrams.pdf

 

That was very helpful. I was able to determine that the wires to the CEM were not connected.

However, the plot thickens:

What are these wires in the CEM wires place?

I am confusion. Lol.

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I have seen instances where the terminals for the wires at the pedal and CEM need to be replaced. These are pins 1-3 at the pedal. I remove them from the connector, cut the ends off and splice on a repair terminal. Looks like someone might have tried something similar but I don't know why there are bare terminals there.

Are the yellow, white and brown wires cut? I'm not able to tell from the picture. Those are the wires that should go to the CEM

 

The wires themselves aren't cut, but they have been pushed out of a connector with a screwdriver and pushed to the side.

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So here is what I have deduced based on wiring charts and what not.

It appears that those extra wires go to the CEM, like maybe the original ones went bad or something.

Wires 4-6 are original, 1-3 has been replaced with thicker wires.

When pulling the pedal off, I found that the connector was loose and not clicked into the pedal. I pushed the wires onto the connector better and I pushed the connector all the way on.

Don’t wanna speak too soon, but I haven’t had an issue since.


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So it sounds like instead of using the Volvo repair terminals, they ran new wires directly to the CEM. Or at least to the CEM connector. You can check those to see if you see the same sort of thing. I don't remember the connector off hand.

 

The accelerator pedal has a redundant signalling system. One is a digital signal and one is an analog signal. Both have to be present and working to be plausible.

When terminal contact in connectors is poor, replacing the connector’s terminal with a repair terminal (already crimped to a pigtail) is the proper fix, but it should be connected to the existing wire with solder and insulated with heat shrink for a permanent repair.

Joining wires using crimp connectors is unreliable long term.


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Volvo's approved method for joining cables uses heat shrink butt connectors, not solder. They are very reliable long term.

 

Can you elaborate on the symptoms of the pedal issue?

My V50 seems to give me throttle related trouble at random, mostly when it's cold. It has approximately 4 levels of failure that I have determined:

Level 1 - Kicks out the Cruise Control with a sudden jolt. Cannot reset the cruise after this for at least several minutes or sometimes until engine restart.
Level 2 - Kicks out Cruise and throttle response is dampened. Still get full power, but shifts are jerky due to delayed throttle mapping.
Level 3 - Cruise Control unavailable and "Reduced Engine Performance" shown on cluster. Throttle is super slow and car struggles to get to highway speeds.
Level 4 - Car suddenly loses all throttle plate control while driving. I can mat the pedal and it just idles. Key Off / Engine restart required to get moving again.

At no point do a I get a Check Engine Light. I have not interrogated too much with VIDA, but the times I've checked it did not have any throttle related codes logged in the ECU. Maybe I should be checking the CEM.
Not knowing the common failure point, I was thinking it was more probably a throttle body failure. Mostly because these failures have happened to me while in cruise (not even touching the pedal).

 

The one's I've repaired had codes for the pedal signal and a warning message. I don't remember anyone complaining of it coming out of cruise but it would make sense that the car would disable cruise if it doesn't see a reliable signal from the pedal.

 

Yeah. I only use the cruise, like...all the time. So it's annoying when it kicks out. I then have to hold the pedal down with my own foot! Like a CAVEMAN!

 

What I was experiencing was Level 2 and 3.

What was happening to me was I was driving along, and it felt like the car lost power. Many times it would happen while shifting.

Level 3, as you put it, would kick in, and i would have to floor it to get any kind of acceleration.

Just give your connector for the gas pedal a good measure check. Its 3 10mm bolts-2 on the top and one on the bottom. It can't hurt to make sure its all snug and wires are in the connector tightly.

 

Will do! I hope it's that simple.

What I can't comprehend is why there isn't even a CEL on the dash. Obviously the throttle control system is having faults - a pretty big safety concern. If it were a VW or Toyota, it would fault hard, light up the dash and not quit until you cleared the code. I guess I appreciate that it can recover on its own, I'm just not sure how they get away with that from a life safety perspective.

 

Will do! I hope it's that simple.

What I can't comprehend is why there isn't even a CEL on the dash. Obviously the throttle control system is having faults - a pretty big safety concern. If it were a VW or Toyota, it would fault hard, light up the dash and not quit until you cleared the code. I guess I appreciate that it can recover on its own, I'm just not sure how they get away with that from a life safety perspective.

The reason is not because OBDii doesn't support it, but that whole 2 feed thing. If BOTH feeds die, that's gonna trigger the check engine lite more than likely.

In my case, only one feed to the CEM was failing. The feed to the ECM, which I am assuming most cars only have, was still good.

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Situation update: it’s back.


After I hit a quite large pothole today, the message returned. It has returned every time I’ve driven the car since.

It’s too freakin cold for me to go out and take a look, but what are the odds that this is really an issue with the connections to the CEM?

I hit the pothole on the passenger side, where the CEM is located.



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I've repaired a few by replacing the terminals at the pedal and CEM after the pedal was already replaced and I haven't had them come back.

 

I've had a lot of faults just recently. Possibly related to the seriously cold temps (a couple days with temps below 0F). I am able to adjust the descriptions of the fault modes a little more:

Level 1 - Kicks out the Cruise Control with a sudden jolt. Cruise can turn on ("Cruise" light), but will not "set". I can clear this fault with 1 push of the clutch pedal. No reduction in power. Unnoticeable without cruise set.
Level 2 - Kicks out Cruise (if set) and throttle response is dampened. Power is somewhat reduced and shifts are jerky due to delayed throttle mapping. Cruise cannot even be turned on or set. Requires key-off to clear (can be cleared while driving, key removal is not necessary).
Level 3 - Cruise Control unavailable and "Reduced Engine Performance" shown on cluster. Throttle is super slow and car struggles to get to highway speeds. Possibly same power reduction as Level 2, but I think it's worse.
Level 4 - Car suddenly loses all throttle plate control while driving. I can mat the pedal and it won't come off idle. Key Off / Engine restart required to get moving again.

I've experienced two instances of Level 4 failure recently. Never more than once per drive. I also have had several Level 1's and Level 2's in a row. They never seem to mix. I'm pretty sure it's always one or the other. I'm wondering if it's actually 2 different issues (throttle vs clutch position sensor). I will be getting VIDA back up and running on my laptop soon to look for faults.

 

Levels 1 and 2 can be explained by a faulty clutch pedal sensor. Worth checking.

 

I checked the CEM, and the white tagged wire was loose. Loose enough to move in and out of the connector about 2-3 mm. I pushed it back in and secured it.

Problem seemed solved.


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Status update: The loose wire was the culprit. Since my last post, I have not had any issues


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Just to add my 2 cents; a friend of mine had similar problems with Throttle Pedal; bought another of Ebay, obviously problem not solved. Checked Fuse - not blown, then stumbled upon this thread. I had a look at the connector on the CEM, wiggled it a bit and problem 'solved'. (not sure it was the brown or green connector, but I took both off and reattached)

We did check the analog and PWM values by reading out the computer. Only analog seem to work reliably. PWM signal was spurious.

At one point it needs the new terminals/wires soldered to it (I pressume it might fail again in the future), but to other users with same problem; this is probably your best bet if you have problems with your throttle/ accelerator pedal. Wiggle/check the connector on pedal side and CEM side.

His is a 2005 S40 with the 2.0 Diesel Engine.