DRL & Pop-Up Problems

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Jaster
Knows an Aerodeck isn't a 480
Posts: 287
Joined: Wed Dec 30, 2009 5:33 pm
Location: Oxford

DRL & Pop-Up Problems

Post by Jaster » Sat Jul 02, 2016 7:43 pm

I'm having some problems and I would be much obliged if anyone could shed some light (sorry!) on them. I'll try to provide as much information as possible here:

Symptoms:
1. Left DRL works in 21w mode but not 4w mode. Right DRL fine in all modes.
2. Pop-ups won't raise. If manually raised they will return into the bonnet from whence they came when they are switched off.

My investigations so far:
3. Tried a variety of DRL bulbs (including some from a Volvo specialist - I believe they were Lucas).
4. Checked continuity across DRL bulb holders, all OK.
5. Checked voltages in front and behind DRL sockets (black rubber behind holders), all OK right side, no voltage to 4w pin on left side.
6. Removed pop-up relay and bridged connections, pop-ups operate normally (regardless of bonnet switch position - not sure if this is normal).
7. Opened pop-up relay and manually actuated the connections - pop-ups go up and down fine.
8. Switched off the headlights while watching the open relay - observed the relay closing as the pop-ups retracted and then opening again once they had returned.

My thoughts:
9. Can't figure out the DRL problem. Ground seems fine since the 21w mode is working. Having said that, probing between the 4w pin and ground gives 0V, but probing between the 4w pin and the -ve battery terminal gives approx. 0.03V.
10. Bonnet switch seems to be working normally - with the headlights manually raised, switching them off and closing the bonnet switch causes them to lower, so I think I can rule that out.
11. Pop-up relay seems to work, based on evidence of it functioning when closing the pop-ups. Looks like it's not getting any input when the headlights are switched on.

Possibly unrelated - if I remove and then re-attach the DRL bulb holder while the ignition is on, I can hear the rear fog changeover relay clicking. Not sure what to make of that one.

I know that the previous owner of my car had what I believe to be the same problem, and that he tracked it down to a break in the connection to the bonnet switch. I'm not pursuing that line of investigation this time due to my reasoning in point 10.
Current: '94 GT & '88 ES
Former: '89 ES

Alan 480
480 Is my middle name
Posts: 918
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: DRL & Pop-Up Problems

Post by Alan 480 » Mon Jul 04, 2016 11:57 am

bonnet switch is designed to PREVENT the motors turning when bonnet is open, to save your fingers, BUT TBH if you are getting some movement try hot wiring the switch under the bonnet catch, it lives in a pretty grotty area and loads of water etc
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

User avatar
Jaster
Knows an Aerodeck isn't a 480
Posts: 287
Joined: Wed Dec 30, 2009 5:33 pm
Location: Oxford

Re: DRL & Pop-Up Problems

Post by Jaster » Mon Jul 04, 2016 4:48 pm

Yeah - what I meant by point 10 is that the bonnet switch is working normally, in other words they headlights don't retract with the switch open, but do with it closed, so I am discounting it as a source of the problem.
Current: '94 GT & '88 ES
Former: '89 ES

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