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stroud_omnibus
09-18-2014, 03:26 PM
Several months ago I posted on here about an electrical issue I have. It causes the headlights to flicker/ strobe but only at speeds over 40mph.

I went to see Dennis's (lindenengineering) brother Gordon, and he suggested pulling the ABS fuses ans see what happens. Last night I did just this and no flickering headlights!

Any ideas as to which component can cause this? I suspect that whatever it is, is causing problems with the current as far back as the battery as a separate fuse box for the after-market body electrics is getting a dose of this 'bad' current too.

Thanks!

Aqua Puttana
09-18-2014, 03:42 PM
Several months ago I posted on here about an electrical issue I have. It causes the headlights to flicker/ strobe but only at speeds over 40mph.

I went to see Dennis's (lindenengineering) brother Gordon, and he suggested pulling the ABS fuses ans see what happens. Last night I did just this and no flickering headlights!

Any ideas as to which component can cause this? I suspect that whatever it is, is causing problems with the current as far back as the battery as a separate fuse box for the after-market body electrics is getting a dose of this 'bad' current too.

Thanks!
Gordon was smart enough to suggest pulling those particular fuses so I'm certain that he had reasons. Have you called him and asked what the next step is?

Keep us updated please.

vic

stroud_omnibus
09-18-2014, 04:13 PM
Vic, Gordon suggested those as the symptoms were purely speed related and the ABS is, as you know, how speed is monitored on a Sprinter.

I have called Gordon today and will be seeing him tomorrow. He thinks he may have a code reader that will fit, but maybe not. We'll have to see.

I'm not going to start throwing money at this until I can narrow down what is causing the problem.

Aqua Puttana
09-18-2014, 04:39 PM
Vic, Gordon suggested those as the symptoms were purely speed related and the ABS is, as you know, how speed is monitored on a Sprinter.
Kinda, sorta. The speed is monitored by the modules and the conditioned signals are used for the ABS to do its job.

In my T1N the ABS system has a heavy 40 amp fuse and some smaller rated fuses (25 and 7.5 amp). The larger fuses feed the ABS pump and other higher load devices within the ABS. I don't have any specifics because I've had no reason to investigate that yet. My guess would be that it would take something involved with the highest amp circuit to cause a noticeable overall system voltage fluctuation. For me, the smaller amperage control fuse devices like the wheel speed circuits are less likely suspects.

62484


I have called Gordon today and will be seeing him tomorrow. He thinks he may have a code reader that will fit, but maybe not. We'll have to see.

I'm not going to start throwing money at this until I can narrow down what is causing the problem.
I wouldn't throw money at it either. Some testing is needed.

vic

stroud_omnibus
09-18-2014, 05:00 PM
That's useful info Vic. I took the 40, then the 25 amp fuses out which put the ABS and brake fluid level lights on, then took out the 7.5 and this put the EDC light on. So I put the 7.5 back in just in case it caused Limp Mode.

I think I'll try the 40 and 25 individually and see what happens.

stroud_omnibus
09-21-2014, 12:45 PM
Right, pulled the 40 then 25 amp fuses separately last night. Both gave the same result, no flickering of the headlights (which is good!) but still none the wiser as to which circuit is responsible or whether the ABS pump itself is the problem.

Couldn't locate Gordon to try and read for codes but will most probably take it to the dealer as STARS will go more in depth I hope!

lindenengineering
09-22-2014, 12:56 AM
Alan
We had a chit chat about your ABS problem over a transatlantic phone call although the NO vote and Labor in Scotland was the focus of the discussion!

Gordon considered the ABS frequency had something to do with the flickering which I believe was determined by disconnection.
Now from my experiences and one we had last week I have reason to think you have a circuit fault in the ABS brick itself.

We had a 2005 unit in with an ABS fault showing no signal condition on the left hand rear sensor/hub. Exposing the sensor and tone ring although nothing seemed amiss we cleaned it, and made sure the air gap was good. With scanner on it for a road test it threw an immediate code--same fault!
To be on the safe side we installed a new sensor, jacked up the wheel put it in gear and it then showed Rht front fault--drive it up the street and same original fault rht hand rear fault! Hmm!

OK out with the headlamp remove the ABS multi pin socket ohm out all out then check with an oscilloscope, all signals intact.
Having reconnected it we cleared the codes and this time we got our old favorite fault back --that hoary old problem return pump fault!

I suspect the circuits in the brick are compromised and once the unit sees a threshold frequency it thinks there is a skid/wheel slip condition and it is trying to activate the ABS return pump which is pulling power directly from the main circuits through the +ve feed to the brick. Hence the flickering.

However before doing anything I would check the integrity of the earths/grounds because experience tells me that many a confusing problem with DC voltages and circuits on vehicles can be attributed to poor grounding of circuits.

Gordon is about, but off to Bath on Monday with Steph to celebrate his 60th in the new hot springs resort complex they have built.
For those who don't know what the City of Bath or Aquae Sulis Roman Baths here's some info.

http://whc.unesco.org/en/list/428

For Brits who have never seen or heard of Glenwood Springs here's the Colorado equivalent:-
http://www.hotspringspool.com/swim.
Maybe it will be a world heritage site in a 1000 years!

Allen its just the spot to sooth aching limbs after a session on the nearby ski resort of Sunlight--then a wee dram of Scotch by a roaring log fire--"lubricating" parts that need lubricating!:thumbup:

Allen if all fails I think you will have to consider a new ABS brick. Let us all know how you get on!
All the best
Cheers Dennis

stroud_omnibus
09-22-2014, 09:47 AM
Hi Dennis, thanks for the info, it all helps in narrowing down the fault. With the situation you quoted, the vehicle was already showing an ABS fault so I assume the light was on. My light hasn't come on except when I've removed the fuses and they go out again once replaced.

I agree that this could be an earth issue, but where is it? I can see the multi-pin plug with a loom about half an inch thick coming out of it so would I be correct in saying the earth wire is in there? Whereabouts would it exit this loom to the body? I have checked/ cleaned as many earth points as I can locate and all are good.

I will try and see Gordon later in the week.

lindenengineering
09-22-2014, 10:54 AM
Allen
Do you need a wiring diagram for the ABS system?
I could shoot you one over by e mail.
D

stroud_omnibus
09-22-2014, 02:07 PM
Hi Dennis, I would be grateful if you could send me a wiring diagram. I do have a basic schematic one from the downloadable manual often referred to on here. I did have a look at it after I sent my last post and it shows earth points behind the headlight. If this is correct then these have already been checked and are good.

I'm no 'sparky' so can't get it into my head how current can flow from a power source (ie: battery) to a component for said component to then feed 'bad current' back which in turn affects something else connected to it. Weird!!

email: stroudomnibus (AT) btinternet (DOT) com

lindenengineering
09-22-2014, 02:28 PM
OK
I will shoot you one from Snap on Shop Key/Mitchel.

Its a true representation of the schematics and circuitry but devoid of the all factory add on stuff like clips, bolts, etc.
With the socket removed from the brick its an easy pin out !
Cheers Dennis