Engine Bay Relays

[XJR-S]

Well I tracked down an intermittent starting problem to the starter motor relay. I've never pulled any of the engine bay relays before (more fool me) and have discovered that all of them are corroded. The starter relay was actually dripping rust out from inside. I need to do some serious work overhauling the relays here as reliability is an issue!

I've also spotted my fan run-on diode has started to melt the relay holder from poor connection, so averted a disaster there.

Why would anyone put so many relays in harms way?!

[Brakebuster]

well , they are 24 years old........

and at the time, it was how it was done


the joys of classic cars


tinkering does have its rewards


BB

[XJR-S]

Yeah you are right BB.

Doesn't help the relay cover was cracked. I'm going to fiberglass it up and make it pretty again. And water tight.

Just got back from a local auto electronics supplier who has ordered in 5 relays for me. £5 each which isn't too bad. That said, original Jaguar badged relays from DMG are only £9. But spending that on relays seemed a little unnecessary.

The baking soda will be coming out this weekend to clean all of the relay holders then put terminal protector on them and re-assemble. One by one. That's going to be a barrel of fun!

[tommad]

Hi,

I was wondering if anyone could tell me exactly where the starter relay is on a 4.0l Manual ('93 so post facelift). I have had intermittent starting problems where I turn the key but nothing happens; this has usually "self corrected" but now nothing at all. Car has power and lights etc work, but nothing when key turned to second ignition position (no cranking etc). Can start the car by getting power directly to starter motor and then it runs fine but this is a little inconvenient when popping to shops etc.
I have seen quite a lot of pics of this relay in older cars but not the facelift versions and although I can see lots of relays in the engine bay, not sure which one it is. I realise the problem may be elsewhere but wanted to start simple and gather this relay can be a problem...

Any advice much appreciated and thanks in advance!

TM

[ptjs1]

tommad,

It's the rear one of the 3 relays on the right hand side inner wing.

As a suggestion, also check the positive and negative bulkhead terminal posts on both L & R sides of the bulkhead. They are prone to corrosion and poor contact. Try checking voltage and continuity of these posts compared to direct voltage readings off the battery. Also check for slightly loose connections on the battery itself.

Good luck

Paul

[tommad]

Dear Paul,

Thanks for the quick response, I'm consistently amazed people take the time to reply on forums such as these, but it's certainly great that you all do.

I think the actual battery terminals are OK as I checked and cleaned those before tightening them. The terminal posts on the bulkhead I have not specifically checked properly; I know the one on the left is a little corroded, but that was where I ran a wire from to the starter to get it going. I am not sure if that means it's OK or not but will definitely check those now.

If it's not that or the relay then I presume it might be a problem with the actual ignition switch/barrel on the steering column? This will be beyond my abilities and will have to take it somewhere.

Thanks again,

Tom

[ptjs1]

Tom,

Both the positive and earth connections on the starter can be prone to ageing deterioration. But if a direct feed from the bulkhead overcame the problem, that would seem to eliminate the earth connection.

There are some ways that you could at least investigate a problem with the ignition switch, such as checking current flow to the relay terminal etc. Check back in here with your progress and I'm sure one of us can make some suggestions as to where you might look next.

Cheers

Paul

[tommad]

Hi Paul,

Following your advice I had a fiddle with the starter relay, pulled out and cleaned contacts (which were filthy), and after this it started. I am thinking I might replace it at some stage as looks pretty knackered, but hopefully that's the genuine cause of the issue and it's not just coincidence it started working again!
However, as is often the case, resolving one issue means another (probably more serious) one cropped up a few weeks later. Having been using it a bit recently, but yesterday when I got home I noticed quite a strong fuel smell inside the car and especially when got out. It was dark so didn't investigate initially. However, this morning there is fuel on the ground and when engine running fuel is spraying down from the rear (approximately where the rear seats are and possible slightly to the right, but cannot get fully under car).
Anyway, I will post this issue in the "Fuel System" section and see what people say. As it sprays when the engine is running I presume it's a fuel line rather than tank issue, but who knows...

Thanks again for the help,

Tom