N52 130i LCI 5V Reference 1 Accelerator Pedal Issue

[Frostburn]

Hi, I've recently had trouble with poor pedal response with it being laggy so I checked the codes and it came up with a bunch of pedal and throttle valve related ones, (2CF9, 2CFA, 2D09, 2D1D).

For context the car had a tyre blow out and multiple limp modes due to a dodgy battery then sat for a whole, and this is all happening after a new battery and trying to get it running again. Everything else works fine just the pedal is the issue.

I replaced out the throttle valve and the pedal and it's exactly the same, I've had a cloned DME fitted and swap between the two but it's the same. I've checked the voltages on INSTA and with the original pedal connected the 5V reference one is 1.23v with a different pedal (not exactly the same connector position but same connector) it's 3.27v. When the pedal is disconnected INPA shows both voltages at 5V.

Assuming it's some sort of voltage drop somewhere, I unplugged the eccentric shaft sensor, MAF, TPS but it still 1.27 with the pedal connected. Is it possible both pedals a faulty given they show different voltages? I'm unsure how to proceed and would appriciate some help, thanks.

[tpl.mallon]

That’s almost certainly a 5V reference issue, not bad pedals or throttle bodies.

If you’re seeing full 5V with the pedal unplugged but it drops hard when plugged in, that usually means the 5V ref circuit is being pulled down somewhere (short to ground or high resistance).

Since unplugging MAF, eccentric shaft sensor, etc. didn’t bring the voltage back, I’d be looking at:
• Wiring damage (especially after the blowout/sitting)
• Short in the 5V ref line to ground
• Corrosion or pin fitment issues at the DME connector

Very unlikely both pedals are bad, especially with different readings.

At this point I’d trace the 5V ref wire from the DME to the pedal and check for voltage drop/shorts under load.

[Frostburn]

Originally Posted by tpl.mallon

That’s almost certainly a 5V reference issue, not bad pedals or throttle bodies.

If you’re seeing full 5V with the pedal unplugged but it drops hard when plugged in, that usually means the 5V ref circuit is being pulled down somewhere (short to ground or high resistance).

Since unplugging MAF, eccentric shaft sensor, etc. didn’t bring the voltage back, I’d be looking at:
• Wiring damage (especially after the blowout/sitting)
• Short in the 5V ref line to ground
• Corrosion or pin fitment issues at the DME connector

Very unlikely both pedals are bad, especially with different readings.

At this point I’d trace the 5V ref wire from the DME to the pedal and check for voltage drop/shorts under load.

Much appriciated for the help, I've measured the voltage on the Throttle body connector and it's also the 1v value, would you know which pins of the msv80 would control theat reference 5v I've had a look and I think it would be pin 24 but unsure

[tpl.mallon]

Originally Posted by Frostburn

Much appriciated for the help, I've measured the voltage on the Throttle body connector and it's also the 1v value, would you know which pins of the msv80 would control theat reference 5v I've had a look and I think it would be pin 24 but unsure

The 5V reference issue is confirmed by the low voltage at both the pedal and throttle body.

Pin 24 on the MSV80 DME is one of the 5V supply pins for the accelerator pedal module.

Test:
Ignition ON, engine OFF:

1. Disconnect the accelerator pedal.
2. Measure voltage at DME pin 24 → expect ~5V.
3. Reconnect the pedal and re-measure pin 24.

- Voltage drops to ~1V at the DME? Likely DME internal fault or harness short to ground.
- Voltage stays ~5V at DME but drops at pedal? Wiring issue between DME and pedal.

Please report the voltages from both steps.
Inspect DME connectors for corrosion or bent pins in the meantime.

Let me know the results.

[Frostburn]

Originally Posted by tpl.mallon

The 5V reference issue is confirmed by the low voltage at both the pedal and throttle body.

Pin 24 on the MSV80 DME is one of the 5V supply pins for the accelerator pedal module.

Test:
Ignition ON, engine OFF:

1. Disconnect the accelerator pedal.
2. Measure voltage at DME pin 24 → expect ~5V.
3. Reconnect the pedal and re-measure pin 24.

- Voltage drops to ~1V at the DME? Likely DME internal fault or harness short to ground.
- Voltage stays ~5V at DME but drops at pedal? Wiring issue between DME and pedal.

Please report the voltages from both steps.
Inspect DME connectors for corrosion or bent pins in the meantime.

Let me know the results.

So the pin 24 from the DME outputs a solid 5V regardless of the pedal is connected or not. Part of me is still leaning into it being a pedal issue given that they drop it by different voltages and is the only componant to drop the voltage on the line. I guess all I can do now is inspect the wiring? Where would I start?

[tpl.mallon]

Originally Posted by Frostburn

So the pin 24 from the DME outputs a solid 5V regardless of the pedal is connected or not. Part of me is still leaning into it being a pedal issue given that they drop it by different voltages and is the only componant to drop the voltage on the line. I guess all I can do now is inspect the wiring? Where would I start?

DME putting out solid 5V even with the pedal plugged in means the ECU is fine. The drop to ~1V is happening somewhere in the wiring after the DME.

That also explains why the two pedals drop it by different amounts
they’re loading the shared 5V reference circuit a bit differently. Not both pedals bad.

Start with the easy stuff:

1. Unplug the pedal connector under the dash (driver’s side near firewall). Check both sides of the plug for green corrosion, bent pins or bad contacts. Clean it properly with contact cleaner.

2. Pull the carpet back a bit on the driver’s side and inspect the harness where it passes through the rubber grommet in the bulkhead. Look for chafed wires, rubbing or corrosion. The tyre blowout and car sitting often causes trouble right there.

If nothing obvious, with the pedal unplugged measure resistance from the 5V pin at the pedal connector to ground
it should be very high (thousands of ohms). Low number means a short in the harness.

Do steps 1 and 2 first. A lot of these N52 cases get fixed there.

[Frostburn]

Much appriciated for all your help, but a different pedal fixed the issue..i think the second pedal that was slightly different wasn't compatible, when though it was a good pedal, another one that is exactly the same gives a solid 5v