Hi All,

Does anyone know what Fuse 26 (20 amp) does in the engine bay of a 2013 UK-spec V8V? My manual states it's for the "Headlamp wash pump (HID only)," but my car doesn't have this option.

I am investigating another fault (discussed in a different thread) that only occurs when Fuse 26 is connected or live. I found the original fuse was blown, so I replaced it, which then triggered the issue.

The fault seems to be related to the Secondary Air Pump (P2258). I also discovered that Fuse 31 (40 amp) was blown. When either fuse is connected or live, the car enters limp mode, and I get the P2258 error code.

TIA,

 

Fuse 26 is exclusively used for the washer. Otherwise is sits useless with Fuse 25.

If you Fuse 31 is blowing and giving you P2258 (circuit HIGH) on the 2ndary air injection system, and this only happens when both fuses are replaced, then I would look at the fusebox itself, is the connector underneath adjacent between the two, and if there's some sign of water ingress / corrosion around there at the connector under the box. Or follow the wires if they are joined and see if there's chafing somewhere.

N

 

Thanks N.

​​​​​Its a weird one. Neither of the fuses are blowing.

When fuse 31 or 26 are installed (I found they were blown) I get limp mode and code P2588. Either fuse by itself is brings the error on.

If I remove the fuses and clear the code, It doesn't come back. But I get a P0137 error which is related to the Secondary air pump not working. I have replaced the 02 sensors already.

Could be the secondary air pump has failed, but I can't understand why fuse 26 would make any difference to it.

You mind me asking where you found the wiring diagram?

Thanks,

 

Hi everyone,

I wanted to share a quick update for anyone who might find this helpful in the future.

With UltraMarine's assistance (thanks again for your time), I managed to remove the Engine Bay Fuse Box. It was a bit tricky, but overall, not too difficult. The terminals underneath, which connect to the 80 Amp fuse, showed signs of water exposure, so they needed a thorough cleaning. I opened the fuse box as much as possible and cleaned all the accessible contacts. I also removed and cleaned each of the fuses and serviceable relays (1-8). Unfortunately, the relays above that (9+) aren't serviceable, so replacing the entire fuse box would be necessary if they fail.

The 80-amp fuse terminals, in particular, required extra attention. It was clear that a small amount of water had entered the casing at some point.

A replacement fuse box is roughly Ł300, but since they’re currently out of stock, I decided to refit the original box. To my surprise, everything seems to be working. Relay 12, which controls the secondary air pump and isn't replaceable, now appears to be functioning as it should. I'm getting a consistent 14 volts from fuse 31 (40amp) when the Secondary Air Pump is called upon during a cold start. No issues are showing from fuse 26 either, leading me to suspect there may have been a bad contact or short there previously.

Upon starting the car, several error codes appeared, confirming my suspicion that the Secondary Air Pump is faulty. This would explain the following issues:

• Rough cold starts
• "Urgent Engine Service" errors and Limp Mode (which only started after replacing fuse 31)
• The persistent P0137 code, despite changing the O2 sensors

When I get a chance, I’ll remove the Air Intake and provide another update for future reference. Pics below:

 

Excellent....another useful thread bookmarked should the need arise. Thanks!

 

Glad you sorted it out! I had a hunch it was water ingress in the fusebox. There may be ways to get a near-new box online from the yards: https://www.laglobalparts.com/Catalog/Details/35192 (though this one is sold out). If you do get a spare / repair, it might be worthwhile looking at electrical potting compound on the bottom of the unit to make the underside waterproof, and use some dielectric grease on the connector seals to make sure it doesnt let in water on the bottom connector!

Also. the external relay (#1 below) on the side is for the Secondary Air Injection Pump, you may want to test the coil terminals with 12VDC on to make sure it clicks on and starts the pump, could be the reason why you're getting the Circuit high and MAF error (no air volume detected)




Hope you're back on the road asap!

 

Thanks, UltraMarine.

From what I can gather, it seems that AM replaced the external relay (part no. 1 above) by integrating it into the fuse box. I looked into this earlier, and it appears that there was a change around MY 2010/2011, as there are two types of fuse boards available for the engine bay.

The snippet above mentions "Relay 12 ------ Fuse 31 (40amp) ----- Secondary air pump." I've seen this referenced in several documents as well. Photos of cars from 2011 onwards seem to show an empty space on the bracket where the relay would have been. I now use that space for my battery maintainer SAE plug!

 

Makes sense! Let us know how you end up faring with the air pumps. Always good to have a solution at hand!

 

Wanted to add that as part of the contact cleaning procedure, Aston Martin recommends the use of Stabilant-22 to enhance and protect contacts. I asked my mechanic and he told me it was legit good even if expensive. It's resold worlwide by Wurth, and made in Canada by D.W.

The 2nd video has good details on how it works



There's also an alternative less $ product Deoxit Gold