F**ked Black Rover 827 SLi - The Mistake Machine

[St.Jude]

New relay turned up.

No fucking good.

Wrong part.

I think it's me. The Honda part number is 100% 39400-SD4-003 but this is 39400-SM4-003.

[DaveDorson]

So does the new but wrong relay function the same but has the wrong pin configuration or do we not know how the relay functions?  Just wondering if a patch lead between old a new (some spade connectors and some wire would work for to test) would perhaps at least get you a start and run situation 

[Rust Collector]

My Prelude isn't going anywhere at the minute (hour/day/week/month/year), I'm happy to grab the relay out of that and check if it has the same pin out for you - if it does then you'd be welcome to a lend of it for diagnostics.

[DaveDorson]

I was sort of thinking if it's just a bunch of switching 12v and 5v signals and triggers using logic it's the perfect use case for an Arduino of some kind and some logic gate programming.

 

I mean I appreciate that you just want something you can plug in and it'll make it work, but if that relay is NLA and made of unobtainium there's a potential real usecase for pissing about with hobby electronics.

Weak lemon drink and thick glasses are entirely optional of course.

[rainagain]

4 minutes ago, DaveDorson said:

I was sort of thinking if it's just a bunch of switching 12v and 5v signals and triggers using logic it's the perfect use case for an Arduino of some kind and some logic gate programming.

 

I mean I appreciate that you just want something you can plug in and it'll make it work, but if that relay is NLA and made of unobtainium there's a potential real usecase for pissing about with hobby electronics.

Weak lemon drink and thick glasses are entirely optional of course.

This sounds like a good solution but if you don’t have the skills/kit for Anduino you could knock up a piece of bread board with more common relay(s) and plug this in with fly leads with male spades. Does anyone have a pin out for the original relay? 

[St.Jude]

Thanks for the offer @Rust Collector but knowing how much they cost I’d politely decline. I’d had for it to be knackered coming over or going away from me!

Ive taken the back off of the old one and it’s just two relays really. I’m going to take the brown plastic off it tomorrow and have a better look.

I’ve got spade connectors somewhere, so I’m just going to “hot wire” the relay connector just to see if it brings it to life. If it does then I’ve some options. Arduino is an option, especially as I’m going to do that shit with the Lada, so it’d be good to try it out. But Ayanamamamama (sp) have new relays as described above, from Japan, for about £50 new delivered. Or just opt for two relays, solder then on to the one I got and throw it back.

I think I’ve got the pin out for the relay @rainagain but I’ll need to check.

[RoverFolkUs]

2 hours ago, St.Jude said:

New relay turned up.

No fucking good.

Wrong part.

I think it's me. The Honda part number is 100% 39400-SD4-003 but this is 39400-SM4-003.

Seeing the picture, that looks remarkably like an old 7 pin Mitsubishi flasher relay! 

Sorry I know that's no help whatsoever, just some useful* pub trivia I felt the need to blurt out 🤣

[RoverFolkUs]

Without re-reading all the replies, most relay problems are going to be dry solder joints or dirty/welded contacts

Though I expect that is going to have a microprocessor and some capacitors inside it so is far from a straightforward relay, but closely inspect everything you can on the PCB for dry joints because I bet that's all the problem actually is with it

[St.Jude]

1 minute ago, RoverFolkUs said:

Without re-reading all the replies, most relay problems are going to be dry solder joints or dirty/welded contacts

Though I expect that is going to have a microprocessor and some capacitors inside it so is far from a straightforward relay, but closely inspect everything you can on the PCB for dry joints because I bet that's all the problem actually is with it

I think it’s had water inside it, there are limescale marks on the inside of the case and one pin especially looks like it’s full of limescale. The solder joints look fine really, but when I take the brown thing off we will see.

[RoverFolkUs]

1 minute ago, St.Jude said:

I think it’s had water inside it, there are limescale marks on the inside of the case and one pin especially looks like it’s full of limescale. The solder joints look fine really, but when I take the brown thing off we will see.

Yeah fair enough, it may be fooked but my internal failed budding* engineer would force me to prise into it and find a way of making it work

Rust can be cleaned off and the joint reflowed, jumper wires if there's damaged traces etc. 

Especially crucial on an unobtainium part.

It's a lot of time and effort but the satisfaction is unbeatable (for me, anyway) in circumstances like that where you find a way of making something work 

*There's a reason I'm a mechanic and not an engineer. That's what people tell me when I curse engineers 😗

[St.Jude]

14 hours ago, RoverFolkUs said:

Yeah fair enough, it may be fooked but my internal failed budding* engineer would force me to prise into it and find a way of making it work

Rust can be cleaned off and the joint reflowed, jumper wires if there's damaged traces etc. 

Especially crucial on an unobtainium part.

It's a lot of time and effort but the satisfaction is unbeatable (for me, anyway) in circumstances like that where you find a way of making something work 

*There's a reason I'm a mechanic and not an engineer. That's what people tell me when I curse engineers 😗

Quite right. I give out about Toyota’s prices for parts but they’re nearly always available. 

Now I’ve got to work to make these things work!

[petermcpete]

I've had relays before where visually the solder joints look fine, but reflowing them has fixed the issue. It's free and doesn't take long, so got to be worth a go as a first pass.

[Rust Collector]

I can't remember if I've posted this previously in the thread so apologies if I'm repeating myself, but on another Prelude I did have main relay failure (identical unit to your one) and re-flowing the solder joints did resolve the issue. They weren't all visually bad, I remember one or two joints looking suspect. I seem to recall it was pretty easy to reflow the solder as the solder pads were huge.

[St.Jude]

I'll give it a flow tomorrow. Came to work without it so can't avail of the electronics stuff today.

[DSdriver]

I feel the need to say "go with the flow" 😊

[sutty2006]

I sent one of the relays off the Carlton to an electrical engineer who said the joints had gone dry. Was ok to look at, but once energy attempts to pass through it would open a split. He resoldered it and away we went. Unobtainable relays deserve a second chance. Lol

[St.Jude]

Here we are:

Had a quick 5 minutes with it, went through all of the joints there with new stuff as well.

I think the bottom left pin (out of the four closest to the camera) has been properly corroded though, there doesn’t seem to be that much of a trace on the board.

Not able to test though as the lad who has the tester has gone home and no one knows where it’s gone. Have added this stuff to my to buy list though.

[grogee]

1 hour ago, St.Jude said:

the lad who has the tester has gone home and no one knows where it’s gone

PUT STUFF BACK WHERE YOU FOUND IT.

grrr

[SiC]

Solder a jumper wire across the broken trace. 

[St.Jude]

1 hour ago, SiC said:

Solder a jumper wire across the broken trace. 

I will if it’s properly borked. 

[SiC]

I would anyway going by the look of those traces. Dependant what that terminal does and how much current it needs to pass through it. 

[MJK 24]

I’ve only skim read, so apologise in advance if this is a stupid suggestion….

If it’s automatic, and not turning over, even with a good known battery, is there a problem with the inhibitor switch?

Cue telling me it’s manual and turns but won’t catch….

[St.Jude]

6 hours ago, MJK 24 said:

I’ve only skim read, so apologise in advance if this is a stupid suggestion….

If it’s automatic, and not turning over, even with a good known battery, is there a problem with the inhibitor switch?

Cue telling me it’s manual and turns but won’t catch….

No it’s an automatic. 

The inhibitor switch is the next thing to check after this relay. It’s just the ECU light doesn’t go off after it does its checks, and the ECU doesn’t display any lights when turned on. Given we have no fuel pump action, the main relay controls both the pump and ECU so I’m thinking the relay is bollocksed hence the issues.

Plus as well in testing the relay the ECU side was dead, and the fuel pump was “sticky”.

But if this is changed then the switch it next.

[rickvw72]

Have you tried starting it in Neutral rather than park? I’ve had inhibitor switch issues before and it’s worked.

[St.Jude]

4 hours ago, rickvw72 said:

Have you tried starting it in Neutral rather than park? I’ve had inhibitor switch issues before and it’s worked.

Yep did that before we took the relay out.

[St.Jude]

Got to the car today, plugged the main relay back in and the ECU.

No dice. Still won’t start. Gives a click then absolutely nothing.

BUT - the ECU light now goes off. That’s an improvement, so I’m inclined to think the relay is OK again. Couldn’t hear the fuel pump so I’ve taken it out to check the relay again just to make sure the fuel relay part is working Ok, or at least strip it and give it a clean with contact cleaner.

The ECU doesn’t provide any lights, so I don’t think the ECU is in fault. So I will now look at the neutral switch and see if that’s now playing silly buggers. I’ve also taken the battery out to charge as I’m not sure it’s exactly flush with angry pixies.

[MJK 24]

You’ve more patience than me.  This carry on would be sending me postal!

[St.Jude]

34 minutes ago, MJK 24 said:

You’ve more patience than me.  This carry on would be sending me postal!

I haven’t enough postal energy to be postal across two cars. So the Land Cruiser is saving this one’s arse - for the moment.

[RoverFolkUs]

Do you have a car that works? 😭🤣

[St.Jude]

7 minutes ago, RoverFolkUs said:

Do you have a car that works? 😭🤣

I do! My Peugeot 107, which is overdue a service actually…