Need Some Help...
 

So I've been trying to finish off my electrics for good and get all the wiring in it's final places inside conduit tube etc. Because of using the donor loom, it's involved alot of shortening & extending wires etc. I've go everything connected up except for the cluster, cig lighter, fog light switch, and fan. I tried cranking the engine to make sure it all still worked and nothing happened :mad:

So I got my trusty multimeter out and started checking readings between the key barrel and the battery. Strangely I get continuity and voltage readings on the live (red) wire when the key is off or in position 1. As soon as I turn they key to position 2 or onto the cranking position, the voltage drops to 0?

I also tested the yellow/black wire at the barrel (which I think is the switched live?) and I get no voltage in any key position. I then checked the continuity between the battery and the yellow/black wire, and again it works when they key is off or in position 1, but nothing past that??

I'm guessing there's something wrong with my switched live circuit as it seems to get blocked when trying to start up? I've had a look at the wiring diagram and the only linked thing I could see to the yellow/black wire is the fan relay but I struggled to work out which one it is in the fuse box to see if there's something not right there :confused:

Any help or guidance where to go next would be appreciated!

Is there an interlock to make sure the clutch pedal is depressed while cranking??

sounds really daft but have you checked that the battery terminals are tight?

The pedal box & cables aren't connected yet so it can't be that as it started and ran ok before when I was testing the edis & megajolt.


They're not mega tight, I'll have to check that just incase. I thought though I should hear the relay's in the fusebox click when I connect the battery? (which I don't hear btw)

Ok went out and check all the terminals and earths and tightened them right up and I still don't get any volts or continuity at the barrel when the key is in position 2 or 3. any other ideas of what I can check to find the problem?

Sounds like you have one of the earths or battery feeds missing.

TT

That makes sense TT, as far as I can tell though the only circuit I don't have connected yet which might be affecting it is for the fan switch. I'm sure I had trouble with this before when I was first trying to get the engine to run and for some reason the fan switch had to be plugged in and earthed for it to work. I need to check the wires coming out of the fan relay but I can't work out which one it is as it doesn't give the number for it in the haynes manual on the wiring diagram (eg IV). Any idea how I can ID it or do you know what the code number or color of it should be in the fuse box?

On Gus's Sierra the fan relay was on its own in a yellow holder, with a fuse built onto the side of it. It would have been under the dash originally.

I had a similar problem.
used a 6 pin universal ignition switch (came with no instruction notes) and after checking with multi meter found the common + supply, acc, on and start pins. Everything works well until one turns the key to start, and nothing happens....
After connection pilot test lamps to ignition switch to check the lights goes on at acc position, again on at on position but when turned to start, the on lamp went off and the start lamp lit! This explained why all systems died when starting and no juice supplied to ecu, coil etc when starting - obviously it will never go.

The solution was a simple jumper wire on the ignition pins to keep 12v continuity on the on position whilst cranking the starter.

Hope this helps:)

Thanks dave, that gives me a good starting point. Cant say I remember seeing a relay that had fuse built into it though. Just out of curiosity though, is that how the wiring looked behind the firewall on gus's completed car or did he put all that into conduit tube right up to the fusebox?

No the wiring is all in conduit or wrapped in loom tape

Thanks dave I thought that would have been the case. Just one of the messier parts of my build at the moment as there so many wires that all meet up at the fusebox coming & going in all sorts of directions!

Anyhow I had a good look last night I definately don't have anything that looks like the relay you posted. The only relay that had it's own fuse on the side in my donor was part of the ecu which I removed ages ago before getting it running the 1st time. Any idea what else I should be looking for as I'm guessing the relay was changed in the later cvh sierra's which had fuel injection like mine?

Looking at the wiring diagrams I cannot see any integration between the original cfi system and the rad fan. Have you had the fan working at all?

Even if the fan was not connected it should have no effect on the engine running as the fan had its own seperate power supply.

Nope I've still yet to connect up the fan and cooling system really. I've had a look at the wiring diagram and as far as I can see the yellow black wire from the barrel goes to:

inst cluster (via fuse 22 - connected & earthed)
anti-theft module (removed)
fan relay (not connected)
power delay relay 5 (removed)
eec4 (removed)
edis (connected & earthed)

I also had a closer look at the fan relay in the wiring diagram and it's wires go:

barrel - black wire changing to yellow/black after a solder joint
fan switch - black wire
battery + (via fuse 33) - red wire
battery - brown wire


so I'm still a bit lost as to why I get continuity on the yellow/black wire at the barrel when the key is in position 0 or 1, but as soon as it goes to position 2+ it doesn't? Like you I can't understand why the fan not being connected would interfere but it's the only thing on the yellow/black route that isn't connected. I've checked all the earth wires for continuity (between the start of the wire and the battery - ) and they all checkout fine. the only other thing I can check I guess is if any of these fuses have gone?

Try this.

With the key in position 0 and the battery connected. Connect the negative of the multimeter to an earth directly on the chassis, and touch the positive of the multimeter to the red wire on the back of the barrel.

You should get 12v.

Touch on yellow wire & turn key to position 1. Should get 12v.

Touch on black/yellow wire and turn to positon 2. Should get 12v.

If you havn't got 12v, touch the meter on the yellow then red wire and check you have still got 12v. If you have I would say the switch is knackered. If you loose all 12v I would have thought a dead short or similar.

To check if it is the switch just use a short piece of wire and short across the terminals on the back of the switch. If you go red to black/yellow dash should light. If you go red to black/blue engine should crank. Connect red to black/yellow & black/blue and it should run.

I'll try this tonight to check the readings again on an earth point instead of directly against the battery - .

I would hope the switch isn't knackered as it's just been sitting there since I last used it a few months ago when I know it was working!

Is there supposed to be an earth of some kind for the barrel itself as from memory I only remember earth wires for the stalks?

No earth wire at the ignition barrel.

Well I couldn't find the multimeter so I've got to do some more digging around in the mess that is my garage.. I did try holding a bit of wire between the red and yelow/black & blue/black solder joints on the barrel and nothing happened :(

Like TT said earlier in this thread I must be missing an earth somewhere. So here's what I've got, does it anything jump out as missing?

1) battery - to battery tray (chassis)
2) big black wire from the starter bolted onto the gearbox
3) earthstrap going from the back of the head to the battery tray
4) fusebox common earths onto the tunnel
5) edis,megajolt,tps,coil,etc earth onto the on the tunnel
6) instrument cluster earthed onto the tunnel
7) steering column stalks earthed onto the tunnel
8) fuel pump earthed onto the tunnel

I assume in number 2 you mean a black wire from the bellhousing bolt directly to the negative of the battery.

Also are you still using the Sierra fusebox, as I don't recall there being any earth wires directly out of the fusebox.

Out of interest have you tried shorting from the main battery feed on the starter motor to the small impulse connector on the starter to see if it turns over?

Been re-reading some of your posts. Is the battery new / fully charged / in good condition? Your initial test with a multimeter could show 12v because it is using hardly any current. As soon as you apply a load to the battery if it is dead it could show 0v.

Shorting the starter as above would show if the battery is good or bad.

Ya I'm pretty sure the thick black from the bellhousing goes up to the battery negative, think its just bundled in with the thick red for the starter from memory (which is poor lol).

Yup I'm still using the orginal sierra fusebox with all of the redudante relays removed. Theres definately some common earths coming out of it. If you look at the wiring diagrams in the service manual, it shows one in cell G3 on diagram 1 for models after 1990 for example.

No I've not tried shorting the starter and up till now I've assumed the battery is still good as it's fairly new but obviously has been sitting since xmas when I last ran the engine. I'll have to check the charge on it tonight to see if that's the problem.

Ignition switches typically have two 12v outputs. One for essentials fuel ignition etc and another for non essentials heaters etc. non essentials are disconnected when the key is in the start position.
Try putting a small 12v bulb across the battery to check its good while you run tests and fit another with 2 long leads. Tie one lead to battery negative and trace the 12v supply from switch to starter/ ignition unit
I suggest bulbs rather than a meter as you can't damage them! And give a more subjective reading dim etc

Well I check the battery last night and that's definately where my problem is. I put it onto the charger and it said it was fairly full but left it charging overnight anyway. Tried it this morning and wey hey the engine tried to crank for about 2 seconds before dying away. So I guess my battery is totally shot now and not holding enough of a charge. A bit annoying really as it was a new battery that I got from halfords about 6 months ago. I guess all the draining and recharging while trying to get the engine going the 1st time has killed it or it was just too small for the engine in terms of starting amps. Can anyone recommend a better one that won't hurt the wallet too much?

If it is only 6 months old I would have thought it is still in warrenty if you can find the receipt.

They don't know what you have been using it for. See if they will replace it.

Failing that I bought the below. Good batteries, light and powerful. Makes finding a home for it a lot easier.

http://www.ebay.co.uk/itm/Odyssey-PC...em2ebd2 e6f8a

I can vouch for that one, got mine last year and after the winter lay up of 5months my engine fired up 1st time

Light as a feather compared to a normal car battery too

Just check your not drawing current when the car isnt being used first though or your battery wont last no matter what type it is

Ya I think one of these is going to be the way forward. I double checked and the one I had only had 265 amp starting power compared to 360 amps that halfords say should be used for a 1.8 cvh... I'm struggling to really find any other alternatives that are small enough as my battery tray is only 260mm x 160mm (saturn grp one).

So how can I check if it's drawing current while not being used?