Electrical Problem

[andy atterton]

Hi an extreme novice here looking for some advice.

i recently changed the head on my N reg 2.5L diesel bongo due to a crack in the head. put all the bits back on, bought a new battery (it has been sat up for 18-24 months) put the key in, all the pretty lights on the dash came on but when i turned the key there was a click but the starter didn't turn over.

I have followed the advice i have managed to find around the place, and done a few test and changed a few bits that i will now list.

New Battery as mentioned.
Shorted the terminals on the starter motor to see if it turns over which it did.
Checked the voltage on the small connection at the starter. no voltage when key is turned.
Changed the 60A ignition key fuse.
Changed the ignition switch, not by choice but one of the kids knocked it off the window sill where i had left it, doh.

I also took the cover off of the relay on the left of the battery, the one closest to the front, as i was wondering if it was broken. i pushed the contacts together manually and the starter turned over. I assumed that was the problem but to be sure i switched that relay with the other one just behind it which i think is for the engine management system. the second one worked before i switched them (could feel it click when i tried to start it) but didn't work after i switched them, where as the one i thought was broken did work so i guess that rules out the relays. However there is voltage going to the relay when i turn the key but nothing happening.

I'd be grateful for any tests i could do to try and diagnose the problem and i apologise in advance for any important details i have missed out in my description due to a general lack of understanding.

[jaylee]

Start with a simple one.. You say you have a new battery? When all the warning lights came on pre ignition, did the gradually fade trying to start? Clean & tighten all the terminals on the battery & check & clean the terminal on the earth strap that goes to the inner wing...

I'm guessing from what i read you are getting sort of flat battery symptoms, but the battery is fine...?

[wonkanoby]

or worn contacts within the starter

http://www.ebay.co.uk/itm/BONGO-FREDA-2 ... 43af077bc6


fits the regular diesl one,not the one on winterised ones

[g8dhe]

I also took the cover off of the relay on the left of the battery, the one closest to the front, as i was wondering if it was broken. i pushed the contacts together manually and the starter turned over.

That suggests that the starter is OK (although the Starter contacts can sometimes be intermittent and you may have been lucky) and that the wiring to operate the relay is at fault especially if you have changed the Ignition switch - have all the connections been restored correctly ? I would start by checking the IG1 ignition circuit and the fuse;

check this fuse

[andy atterton]

Thanks for the quick replies.

Jaylee - the lights stay strong and constant and the battery terminals seem clean to me but i will check out the earth as you suggested. I wouldn't describe the problem as having flat battery symptoms.

wonkanoby - was wondering about this as a next step. I found something about that on the forums here with a link to a vid and it seems pretty straight forward. However there is no voltage getting down to the starter when the key is turned so wouldn't that mean the problem is something before the starter?

g8dhe – I've checked that fuse and I was working from that wiring diagram which lead me to a couple of questions. Firstly, and probably a stupid question, but is that the right diagram? My bongo is an N-reg so registered 95-96 but that diagram is from 97 onwards. secondly if that is the right diagram is that some kind of inhibitor switch after the fuse on IGN 1? It seems to me it's present on automatics which mine is but missing on manuals. If it is some kind of inhibitor switch could that be faulty and where is it?


Could this be the correct wiring diagram? in this one the same switch is there but after the relay on IGN1. My Dad suggested cutting the wire coming out of the lower right terminal of the relay and earthing it which would cut out the switch but it would also cut the connection to the ECU which I’m assuming would be a bad idea?

[g8dhe]

Hi No its not the right diagram I didn't translate the "N" to a year, but the switch is an option on the manual/automatic, but yes the one you pulled up is the right one! However I would still suspect that IG1 connection as you have changed the switch itself as the first likely point! After that buzz out the wire from the Ignition switch to the relay and check the earth connection to the relay via the inhibit switch , maybe the inhibit switch is operating correctly ?
No don't cut wires - by all means use a temp bypass to connect earth just to prove it, but its better to use a meter and test for an earth connection. They are very cheap these days Maplin or Halfrauds will be about £5-7 quid for a cheap multi-meter.

[andy atterton]

So after looking up the expression "buzz out" and then looking at what a continuity test actually was I went looking for the earth via the inhibitor switch as you suggested but couldn't find it, so I did a few test on the connections at the relay and got these results.

https://docs.google.com/spreadsheet/pub ... utput=html

N/T = not tested and the key position was done step by step as it appears on the left. It’s also worth noting that I reconnected the battery just before doing this test. You'll see that after switching the ignition to on, the white wire still had voltage on it even after I removed the key but if I disconnect the battery this resets it and there is no more voltage until I hit the on position again.

I then removed the white wire from the connector block and connected an earth instead and the engine now cranks over. For some reason there is voltage coming up the white wire which should be an earth for the yellow ignition switch wire. I'm guessing that it’s coming from the ECU and I can only think that the ECU thinks that the gear box is out of park?

Hopefully some of this information is useful. Also the forum seems to think it's your birthday so happy birthday g8dhe

[jaylee]

You wouldn't have an immobilizer wired into the ignition system would you..?

[andy atterton]

I did consider this but there is no way I could have one and not know about it is there? Also doesn't an immobilizer stop the power coming from the ignition barrel (in this case on the yellow wire) before it gets to the starter relay? If I could have one and not realise it is there an easy way to test/find it?

[g8dhe]

I then removed the white wire from the connector block and connected an earth instead and the engine now cranks over. For some reason there is voltage coming up the white wire which should be an earth for the yellow ignition switch wire. I'm guessing that it’s coming from the ECU and I can only think that the ECU thinks that the gear box is out of park?

Hopefully some of this information is useful. Also the forum seems to think it's your birthday so happy birthday g8dhe

Right a bit of alcohol in the blood at the moment, so I might change my mind in the morning, but yes if you removed the White wire from the relay and replaced it with an Earth to the relay, that indicates that the Inhibit switch is not operating, I would take a careful look at the inhibitor switch and is it being operated at the mechanical level first. If you move on one page on the diagrams it will show you the connector location for the switch A1-03 which appears to be down on the Transmission part 19-444 on this diagram http://lushprojects.com/bongopartsmk2/c ... 03.html#34
If you can test the switch itself either by watching the for the +12 volts to go to zero when it operates (or by checking the resistance of the switch with your meter) that will indicate if it is working, otherwise it will be a case of follow the wiring to find out where the break is.