Mixed up +/- leads to battery (RAV4 MK1)

[Horsey McHorseface]

RAV4, MK1, 3 door, manual, UK model. Silly mistake, blame sleep deprivation.

I got a bit of sparking from the battery + terminal, that should have been a warning, but I didn’t realise my mistake until battery had been fully connected for a minute or two.

I’ve now got a brand new Varta battery. Good news is the engine starts and drives. Bad news is a lot of electrics don’t work:

Indicators work on hazard, but not left or right individually. Clocks don’t work, including lumination. Headlights work, tail-lights don’t. Also not working - Interior fan, central locking, wipers, interior light. There’s no doubt more, but that’s all I can remember.

Praying there aren’t terminal consequences to this, and it’s an easy fix like fuses/relays. Owners manual states four locations for fuses/relays:

1/ Close to the drivers right knee under a cover, a dozen fuses here, none appear blown: PWR outlet, CIG, SRS-ACC, Wiper, ECU-IG, Turn & Gauge, AM1, Stop, Tail, Mir-Htr, SRS-B, Horn, Defog.

2/ Passenger side footwell, under cover, there’s just one relay (as far as I can tell, just that). Black and marked 3B08 90987-04002 056700-6780 12v Denso.

Then two further boxes on the right side of the engine bay.

3/ A larger box with a mix of fuses and relays. Some of these have a clear top, and as far as I can tell, the metal elements inside appear not to be blown, and nor do some of the smaller fuses: CDS Fan, RDI Fan, HTR, ALT, H-LP (RH), H-LP (LH), Main No.1, ALT-S, HAZ, EF1, Dome, IGN, AM2. One smaller fuse has blown, marked Radio 15A. There’s also 3 larger relays: E/G Main (grey) 3B08 85925-17010 056700-7770 12v Denso, ST (purple) 3B06 28300-10020 156700-0503 12v Denso, H-LP (brown) 3B07 90987-02006 056700-6912 12v Denso.

4/ Smaller box which has only two of it’s sockets filled with relays. FAN1 (green) I can’t get this one out, in fear of breaking it, so I can’t read the s/n. FAN2 (black) 3B06 90987-02012 156700-9870 12v Denso.

Is there any way of knowing if these relays are damaged, other than swapping them for new ones? Should I swap them all, or one by one, and which ones first? Any advice appreciated.

[Penelope Stopit]

Horrible but could be worse, had a similar problem in the middle of a desert

With the battery connected the wrong way

Did you have the ignition turned on or did you turn it on?

Relays should still work after being incorrectly connected, some relays may have built in diodes connected across their coils and would need checking once all is good, a blown internal relay coil diode won't stop a relay from working

Note that the diode situation above is a maybe, there is a chance that none of the relays have built-in diodes

Not very often but sometimes, a relay may have a diode in series with one of its contacts, a blown internal relay contact diode will stop a relay from working. Chances of there being series contact diodes are slim

Bearing in mind the above, if the ignition wasn't ever on during wrong battery connections, blown fuses or fusible links will very likely be the cause of the majority of problems

If the ignition was on at sometime during wrong battery connections, horrible job to sort out, could be anything

Don't bother looking at fuses, test them with a test lamp

Edited by Penelope Stopit on Monday 11th November 11:03

[Horsey McHorseface]

Sorry, been busy. Thanks for the reply, Penelope. You know your shizzle.

Ignition wasn’t on. However, now I’ve put a new battery in, it’s not starting, like it did before. Starter is spinning fine. Anyways…

So you reckon fuses rather than relays. I re-checked those in the main box in the engine bay, and with better light, I noticed the ALT 100A was broken. It’s one of those with the perspex top, so not easy to see. Turns out the ALT 100A is the ‘main’? Which makes sense, with so many electrics effected.

So I grabbed it with some pliers and yanked it out. This was mistake #2. Apparently you have to split the fuse box, top and bottom, because that particular fuse is secured by a nut/bolt, which you can only get to by getting underneath the top section of the fuse box.

Now there are 4 or 5 plastic tabs, that are stopping me splitting the fuse box. No matter how I try levering them with a screwdriver, they won’t release. This pic isn’t my fuse box, but it shows identical tabs in another Toyota fuse box. Any hints on how to tackle these?

Edited by Horsey McHorseface on Wednesday 20th November 16:47

[Novexx]

The fuse box need to be unbolted before it can be split, scroll down towards the bottom of this page for a step by step with pictures;

https://www.rav4world.com/threads/how-to-replace-1...

[Penelope Stopit]

Novexx said:

The fuse box need to be unbolted before it can be split, scroll down towards the bottom of this page for a step by step with pictures;

https://www.rav4world.com/threads/how-to-replace-1...

Recently viewed the above link in trying to find out how

Is the year ok?

Wasn't sure about it , don't know the vehicle

[Horsey McHorseface]

Novexx said:

The fuse box need to be unbolted before it can be split, scroll down towards the bottom of this page for a step by step with pictures;

https://www.rav4world.com/threads/how-to-replace-1...

That's a MK3. Hopefully my MK1 isn't as complex. He mentions 'clips' in stages 4/5, but offers no real clues on how to tackle them. I have undone the two bolts holding fuse box to chassis, maybe I'll find more bolts tomorrow.

[Peanut Gallery]

Just to say good luck Horsey, my car was flat as a pancake, got a jump from a Corsa - the colour the Corsa used was black for positive, red for negative.

A couple of minutes of trying and failing, then realizing, then trying to tow start the thing, found one very small fuse had blown. Replaced that, everything worked fine, even the battery - after a long drive.

Did not stop the rust though...