glow plug relay / starter solenoid

Check the big f*ck off sized fuses next to the battery.

Yeah, whack off monsters. (top one in there is 80A, 80A?? I ask ya? what does my car want 80A for???)

lol, I blew one up when I was investigating my ignition switch, I shorted the wrong connectors and it went pop.

Took the fuses out and it was only when I wobbled one of the legs on the 60A one and the other leg didn't wobble that I suspected a problem. The window on the top of the fuse didn't show me it was blown, but it was.

erm, well fuse fixed, original problem exists.

-- Billy H

So the starter motor now turns but the glow plugs still don't get energised, correct?

First, check the cabling around the glow plug relay, could be a bad contact or broken wire. I foolishly sourced a replacement glow plug relay not so long ago, to fix an intermittent glowplug related fault, without checking the existing setup. Turned out to be a broken wire making only intermittent contact. Fortunately the cost for the replacement relay was only two quid from a scrappie plus the wasted journey. And that'd be my recommendation for a cheap replacement relay if you have a decent big scrapyard in the area. Try to find out in advance what range of vehicles you might look to scavenge one off (e.g. the relay I scavenged was for a Pug 106 but I took it off a Metro and could also have got one off an AX or Saxo). Or you might find one on eBay.

In message , Vim Fuego writes

If this is the case, check the glow plugs themselves. I once had a faulty plug that caused an open circuit, which prevented the rest of the plugs from heating up. I changed the glows, problem solved.

No no, sorry, same two original problems.

No heater plugs, and no cranking of starter.

:o(

I was asking does the relay control both??

yeah, I'll go see my mate scrappie...

cheers

An open circuit plug couldn't stop the rest of the plugs from being energised, they're all electrically in parallel. An open circuit in the

*path* to the plugs could - or a *short* circuit could pull the rail driving the plugs down to low volts, however that ought to kill the glowplug fuse if there is one.

Not yet mate, you haven't isolated the cause of the problem yet. What about a broken engine earth strap, that would deny a current return path to both the starter and the plugs?

Although you are 99.9% correct with your reply, some ancient four cylinder diesels did actually use a series circuit for their glow plugs...

Chris

Does it click on/off? Bearing in mind the click off is usually about 30s after click on, *not* when the glowplug light extinguishes.

But was it drawing current? You ought to get a reasonable spark if it was, and/or current measured through an ammeter (careful though, it'll blow most ammeter fuses), and/or visible drop in battery terminal voltage either measured on a meter or you'll see the courtesy light drop dim when you bridge the contacts.

What does the battery voltage do when you do that? Anything? What happens to the courtesy light?

Probably neither, probably a single fault elsewhere causing both problems. Broken earth strap still sounds likely. Try providing an ad hoc earth connection with jump lead from engine body to battery negative (that's negative by the way, not positive unless you like fireworks :-) and see what happens if you try starting it then. May well not be a good enough strap to actually start it but should give you some indication.

Don't believe the timer relay is working just because a light on the dash comes on. Check that power is arriving at the relay when you turn the switch. Ditto with the starter. If the answer to either or both is "no", Suspect the ignition switch. Check the wires coming out of it.

Steve

I wondered about that just after I clicked 'Send' :-)

That's not the power as in the supply to the relay contacts (the big thick wire). That should be permanent +12V (worth checking, actually). This is the power as in the switched power supply to the relay on the multiway connector going into it (normally). Helps if you have a wiring diagram.

Ditto with the starter. If the answer to either or both is "no",

Do you ever get an intermediate relay which the ignition switch energises, and that relay then energises the starter solenoid? Just a thought. Unlikely to be the problem here.

Looks like my plugs are in series...

-- Billy H

I've persuaded myself it isn't that kind of problem.

With the relay shorted i.e if I bridge across the terminals, the glow plugs recieve a current and my flasher bulb glow enough to burn my fingers in a few seconds.

The relay has a PCB inside with small capacitors, diodes, resistors and an IC in there also. I am more inclined to think there is a problem in there.

As always though, I could be wrong...

-- Billy H

The nominal operating voltage for these is 11.5v. If connected in series, the maximum voltage attained at the plug would be 3.5v.

I got a little spark. Shorting the female connections on the relay connection (car side) gave an almost welding heat on the two junior hacksaw blades I used for the test :o)

Nothing. It seems this switch is currently making no difference.

When I tested the bus bar for the glow plugs I earthed onto the bonnet catch, so I think I'm well earthed!

-- Billy H

I always had a little light on my clock, oh wait come to think of it I think that is alarm thingy... but anyhow, it comes on when I turn on ignition and it always went off with the 'click' of the relay. Now it comes on and goes off and the 'click' does not occur. I am thinking I have two relays, one a timer, and one the main power bridge. 's confusing and complictaed but it is a little analogous to the old petrol ignitions (those which had distributors in plastic caps), they had two circuits on them; the HT and the LT, isolated through the coil.

It's got me wondering if I have a low current timer feeding a High Current supply for the bus bar.

The Hayne's Manual has helped a little, but I either need to consult it further or it isn't telling me the whole story.

-- Billy H

Mine was a 1988 Citroen BX non turbo- that to me is kind of ancient...

Glow plugs and starters take a *huge* current. More than both headlight bulbs together. If the Earth strap is dodgy you could well find that it works fine for lowish power (single test bulb) but drops so much voltage when a high current is passed that the starter/glowplugs won't operate.

If you want to see it on your tester you could put the wires one on the engine block and one on the bodywork (both are supposed to be 'ground', I know, just try it) and turn the engine over. If it is acting up you'll get a voltage across the ends and the bulb will glow.

Or just unbolt the ends of the earth strap, polish the contact surfaces up with sandpaper/file, cover them in vaseline and bolt them up tight again. Ten minutes work, no cost, then you'll be guaranteed it isn't that. And next time it won't be either.