Lude Generation

Recently it seems that both my horn and radiator fans have stopped working. Car seems to put out lots of 'condensation' style smoke when starting from cold and smells slightly fumey.

The horn wiring within the cabin is good, the horn switch is good, the horns are good, the horn relay and fuse are good, the horns are earthing correctly, but I do get a wierd growing resistance reading on the wire coming out the fuse box and the live wire on the horn connectors. It starts reading resistance of around 440, then grows steadily beyond what the multimetre will read. All the earths give perfect 0 values.

This makes me think its some bad wiring under the bonnet.

Especially that the fans should have stopped working too, and that they share a section of harness makes me think the two issues are related.

However if I unplug the coolant temp sensor and bridge the terminals the fans kick in and the smoking stops, instantly. No fumey smells, nothing. Again the fan wiring reads what i'd expect it to read in terms of continuity, i've also measured each pin of the fan switchs against each pin of the horn switches to check the wires havn't frayed making the two earth on one another. But none of the wires seem to be touching. I can also jump the horn wiring and they work, albeit pernamently on.

The one and only fault code it brings up is 12, EGR. Which makes sense as it isnt connected to anything, somebody at some point seems to have tried deleting the EGR and Charcoal Canister systsems, they physically exist but all the hoses are cut and blocked off. But it gave this fault code before the horn and fans stopped working.

Is there something odd that controls a few systems? My suspicions are from when I had a bad MAF on a Leon TFSI that ran like poo and would give me codes for everything but the maf, as soon as i'd replaced that every other code went and stayed away.

Ludes are a pretty simple electrical setup with stand alone ECU's, rather than a lore modern can-bus interconnected system.
There is only a very limited multiplex system and that doesn't interface with the systems you're talking about there.
What you've described with changing resistance during testing, sounds like damp/water ingress to me, causing a high resistance short (either to ground, or cross circuit).
Worth doing a visual inside the fuse boxes and any/all connectors/relay bases as a simple next check.

Can't quite picture what people have done to the egr valve, can you post a pic?

wurlycorner wrote: ↑

Wed Feb 05, 2020 6:32 pm

What you've described with changing resistance during testing, sounds like damp/water ingress to me, causing a high resistance short (either to ground, or cross circuit).
Worth doing a visual inside the fuse boxes and any/all connectors/relay bases as a simple next check.

Can't quite picture what people have done to the egr valve, can you post a pic?

Very interesting, the horn stopped working when I broke the original squib ring, however the car has also had cruise deleted so although the dash button lights up it doesn't really help me much as i'd heard you can test one with the other. However the new squib ring has good continuity to the horn, the horn switch changes the continuity and the SRS light functions correctly. I had replaced all the fuses in the box thinking it might be something going on there but the connectors all looked dry, no crystalising sediment or anything when I looked although I suppose worth whipping it off and looking a bit deeper.

Thats the EGR valve.

Gotcha on the egr valve now.
If they've only plugged the hoses with a screw, that's likely to be leaking (albeit only slightly).
Can test that on the intake hose by spraying the area around the screw with carb cleaner while the engine is running - if the revs pic up at all, it's leaking. The egr port you could only really check using soapy water, while the engine is running and the egr is commanded open - if you get bubbles round the screw, it's leaking exhaust gas.
If the egr is plugged in, the ecu will only be pulling a code because the egr valve is stuck (not opening/closing at all/fully) it's not a very intelligent system so it won't know that the hose is cut/plugged. You're best off pulling the egr valve off, de-coking it, refitting and re-connecting the hose (put it back to standard and properly working).
None of that is connected to any of your other problems though!

Where abouts are you?

Well its something to go on at least. I'll do that anyway because id rather it works than just sits in the bay doing nothing. I cant remember from my last Prelude but does is the line coming off the top of the EGR meant to connect the other plugged line you can see in the picture?

I'm based in the south west, performance autoworks are about 40 miles or so from me but I want to understand whats going on myself before sending it off to anybody. The Charcoal canister lines aren't even plugged just flopping about.

km666 wrote: ↑

Wed Feb 05, 2020 8:14 pm

does is the line coming off the top of the EGR meant to connect the other plugged line you can see in the picture?

Yep, it does.

If you're southwest based, hook up with @NafemanNathan
He has nothing better to do with his time than to fix 5g's!

Turns out the squib ring must have not come from a prelude as advertised. Figured out I need to press RES on the CC to make the horn work.