Van Not turning over question.

[Timbur]

Hello Robsey,
Thanks for all the info. I've just spent about an hour messing about without seeing your post first. 
Where can I get hold of the Bentley wiring diagram you mention covering the Auto.

I've been going through various components and wiring to try find the fault. One problem is it is still intermittent so difficult to diagnose. What does happen is that whenever it does not crank on the key it does crank by pressing my extra button that essentially bypasses the key circuit. 
I've just pulled out the glove box junction/relay box and found no faults obvious.
I've taken both wires off the inhibitor switch and bridged them bypassing the switch, made no difference.
I've gone to the engine bay junction box and without a full wiring diagram decided to find which cables operate the starter. I disconnected plugs one by one and tried the key start each time. At the time the key start was working. The only connector that stopped it cranking when disconnected was one of the 7 pin round plugs. So I now know which plug is relevant but I didn't go further with out a wiring diagram.

What is frustrating is that when it will not crank by the key, as soon as I have used my bypass switch the key cranking works again. Makes checking the fault difficult. I have thought that the starter solenoid coil may be weak or have bad internal connections, but if that was the case it would not work from my bypass button. I have also in the past swapped good starters with no change.
What my bypass does is literally bypass the wiring loom from the key switch to the starter solenoid, which points to a poor connection or wire/cable with a resistance. 

With winter coming getting out to press the bypass button is a pain.

Any more thoughts? Thanks. Tim
 

[Timbur]

Some more thoughts.
Are the relays in the glove box nothing to do with the starting circuit? Not shown on the wiring dia I have.
What circuit is the relay in the engine bay box part of?
I am thinking of running a wire from the ignition switch 50 to the starter solenoid direct to see what happens, but not as a permanent fixture.

Going to go web search for the US Bentley wiring diagram.

ta.

 

[Timbur]

Just found and downloaded the 1319 pages of the Bentley Manual. keep me busy for a bit finding the right wiring dia. Thanks.

[Robsey]

You mention the 7 pin connector in the rear junction box.
There are two - one for the tail lights, and one for the engine sensors.

If it was a starter solenoid wire, it would be a fat red/black wire.
(That should be a single wire connector).

Relays in the engine bay junction box are dependent upon the engine you have fitted.
Petrol, diesel, carb or injection set up.

There is no starter relay unless it has been retro fitted.

For a DG, petrol carb. The relays control the manifold heater and probably transistorised ignition control unit.

[Timbur]

Interesting. Ta.
The relays in the glove box board - one clicks when the key is turned to ignition, the other clicks when the key is turned to start. They look original fitting and I've owned the van from 5 years old so not done in my time. They also look factory fitted.
In the engine bay box - whilst the van was cranking on the key I disconnected each connector one at a time and then checked if it would still crank on the key. The only plug that stopped it key cranking was one of the 7 pin plugs. All the single wire plugs when disconnected did not cut out the key start.
I used it this morning and sods law it cranked on the every time. That is what happens it will work fine for ages then has a spell of random no cranking. 
I'm going to study the Bentley wiring diagrams now and will look at the engine bay cabling again, in case I missed one, don't think I did.

Thanks for persisting. Tim

[Joelbtdavies]

Halfway through my list of cleaning connections and earth's. I've seen that on my starter motor some sort of plastic lug has snapped off between the earth and battery connection. Is this a problem?

[Joelbtdavies]

After a good clean of everything with Emery cloth the van has started twice ok and I left it running a bit each time. Lots of rust/crap on many connections. Battery voltage was 11v.
Hopefully solved for now but we shall see...
Thanks for the directions!

[Smiffo]

After a good clean of everything with Emery cloth the van has started twice ok and I left it running a bit each time. Lots of rust/crap on many connections. Battery voltage was 11v.
Hopefully solved for now but we shall see...
Thanks for the directions!

Well done Joel


Sent from my iPhone using Tapatalk

[Timbur]

Ok so we are down to one van with a problem now, well done Joel.
Not got much further with mine other than examining wiring diagrams to get more info.
Yesterday cranked every time used.
Today cranked most times but played up twice with no logic as to when.

I'm going to do a deeper explore of the inhibitor switch then try a by pass lead from there to the starter.

Watch this space, unless you have fallen asleep already.

 

[Joelbtdavies]

Unfortunately back to two vans with a problem... Drove for about an hour today, battery charged from just below 11v to about 11.5v. after sitting for some lunch returned to exactly same problem as before. Click with the key turn and nothing more. Gave all the connections a wiggle and re tighten but no joy. Shorted the connection between the solenoid spade and the bolt the battery cable connects to on the starter to start it to drive home, all fine. Still won't start after getting home. 

So of the checklist:
So have we checked / replaced or fitted securely...
1 - Ignition switch. (Potential burnt or pitted terminals).
seems fine to me, and all other connections seem to be working fine. But not exactly sure what I should be checking here
2 - All earth straps (potentially loose, dirty or corroded connections)
cleaned all yesterday. The gearbox nose earth strap was slightly frayed at one point, wrapped some insulation tape round it. Obviously this needs to be replaced but didn't think it was causing the problem as it has been starting fine with it. 
3 - All starter wires. (Again potentially loose, dirty or corroded terminals).
all cleaned yesterday and seemed ok. Though I'm thinking the wire to the spade is the problem...
4 - Have you considered fitting a hard-start relay to take the load off the starter switch.?
Had a look at the possibility of this yesterday. Not against it, but am i right in thinking this wouldn't solve my current problem, but would be good for avoiding future problem?
5 - Do you have a good healthy battery?
Good output voltage. 
As I said before this is at 11.5v now when not running. Is this ok? 

Seems to me the wire between the ignition and solenoid is not working properly for some reason. Any help please. 

[Oldiebut goodie]

[TONYT25T25]

I think if not already mentioned your battery has probably had it, if allowed to drop to 11.5v they rarely recover and get worse over time by not holding the charge, and not enough to start the engine.

[Joelbtdavies]

Perhaps the battery has had it. Although seems more likely my voltmeter's had it! Was given to me second hand...The split charger display says it's over half full. And if it was 10% surely it shouldn't have started the van earlier today and yesterday

[TONYT25T25]

Sounds like your meter then, what reading does it give when engine running, should be in excess of 13.8 if all charging systems ok

[Joelbtdavies]

So got a new meter this morning. Charge across the battery is 12.5v so all good there. On re testing the starter feed wire there is a voltage of 0.9v coming through here when the key is turned. And this should be 12v if I'm correct? Seems the wire is corroded/frayed/not connected somewhere. Complete transparency, I have very little electrical knowledge, should I try and fit a new wire myself or wait to see my father in law in a couple weeks (was a professional electrician and is a
very capable amateur mechanic).