Where is the instrument cluster ground on a 463?

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inkblotz
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I am tracking down some grounding issues and according to the factory manual one of the main grounds is behind the instrument cluster. I have removed the cluster nothing there. I have removed the panel below the cluster (where the pedals are) nothing there. 

Any insight would be appreciated. Mine is a 1990 463 300GD SWB.

BTW my 603 Turbo diesel conversion, earlier this year has proved to be an amazing upgrade.

 

Mark

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

Instrument cluster electrics is grounded through the loom connection, I think. The loom routes to various sensors and the grounding is grouped in a cluster of brown wires and grounded or earthed by the "A - Pillar". If you remove the interior cover by the A-pillar, it should expose the body work and at abot a half height position you should be able to see a cluster of brown wires bolted together; that should be the grounding you are after.

Water ingress can compromise the earthing quality. 

What is the earthing issue you have? 

JASONGDS
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Re: Where is the instrument cluster ground on a 463?

Hope you get your electrical issues sorted, but more info on your turbo upgrade please?

JASONGDS
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Re: Where is the instrument cluster ground on a 463?

If you gently pull out Instrument panel and remove, I think you may see some grounding points there? You can also remove the top of the dash with little effort which might also help?

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Thanks guys for the responses. I have pulled the cluster out and there are no grounding points there. The factory manual speaks of one behind the cluster. That is why I am inquiring. I have located the 2 on either A-pillar and they are factory tight and seem to be free of any corrosion. Perhaps I will remove the bolt clean the post and reconnect.

Since purchasing the G in 2010 I have had an ABS issue where for the first 300ft of driving the ABS works perfectly but then the light comes on and shuts off the system. I have now gone to the expense (over time) of replacing almost every ABS sensor, pump, computer, and everything else, even the battery and alternator (as less than 12 volts will shut off the ABS). Non have cured the problem. So all that is left is wiring and grounding. This is my daily driver the brakes otherwise work fine. But I would like to get the ABS feature working.

RE the engine swap. Mine had the 603N/A in it. I purchased a 1987 300D with 603A with 140,000 miles on it from a salvage yard for $800. I did a year of research prior to making sure I had all the components when I did the swap. The pan/sump from my 603N/A was a direct fit. I purchased off German EBay the crossover pipe from a 350GD to reach the air cleaner. The 603N/As air cleaner is identical to the 350GD with the exception that it has 6 intake manifold holes where the 350 has one large one. I modified my air box to fit it.

Here is a link to my "in the middle of the swap" post: http://www.gwoa.co.uk/forum/463-603na-sump-mated-87-603a

Anyway let me know if you have any other suggestions/location for the grounds.

 

Thanks

Mark

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

There are more of these grouped earthing points in the engine compartment to be found on both side of inner wing.

I am not suggesting you change the following items at my say so but do check the units and connection quality of them.

Check the overvoltage rely (metal bodied tall, squarish body with plastic top-lid cover, housing a 10 amp-blade fuse). Check also the connections to the ABS pump body.

Further information can be accessed on the Mercedes Parts and Service portal on the internet. After registering on line the service costs €4.00 per hour on the WIS (workshop information service) session. Have the chassis number of your vehicle at hand before signing on; you will need this.

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Pistonhead thanks for the suggestion. The Mercedes website is not MAC friendly so I am looking for a workaround to access it. 

I will peruse the various grounds in the engine bay and refresh where necessary.

Mark

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

Hi Mark,

My brother favours MAC's but it has limitations in the market.

I would suggest having the fault code read to point you in the right direction of diagnoses. I have located two more earthing points for you. One is by the steering coulomb, this is the earth point from the ABS switch. The ABS hydraulic pump has its own earth point by the pump. There are a host of other earth points for each of the front, rear and center lock diff solenoids. 

I will make you a list of all the earth points but this will take time. I do not feel an earth point is your problem. How have come to decide this? 

You have mentioned that the ABS works fine for the first three hundred yards; I am assuming that the brake pedal pulsates under hard braking as per normal until after the three hundred yards.

Have you experienced any soft brake pedal on the first pedal application? And the pedal hardening on subsequent applications?

When was last the brake fluid was renewed? Is it dark in colour viewing through the reservoir? 

JASONGDS
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Re: Where is the instrument cluster ground on a 463?

When you reset ABS by pressing the switch does it light stay on?

My ABS , over sensative, works fine until you come to a stop, then annoyingly kicks in, as if road bad surface, replaced a few sensors , and relay but to no avail, suggestions.....

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

[quote=JASONGDS]

When you reset ABS by pressing the switch does it light stay on?

My ABS , over sensative, works fine until you come to a stop, then annoyingly kicks in, as if road bad surface, replaced a few sensors , and relay but to no avail, suggestions.....

[/quote

 

In your case Jason, I suspect your brake fluid renewal is much (if the fluid in your reservoir is dark or black in colour) overdue or the rear brake drums have excessive brake dust and, or may have hub oil leaking into the drum braking affecting the ABS.

It could be sensors too. Let m e do some digging and I will come back.

fixwin38
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Re: Where is the instrument cluster ground on a 463?

hi Mark

ther are 12 grounding points on your G' (lhd) avery large cluster on front bulhead just below windscreen behind and to side of the instrument cluster and some behind the earth connection to the battery another heavy duty cable  links the engine to the body under the footwell also the buttons for the interion light switches in a major ground which affects the instrument cluster

ABS is doing exactly what is should to identify a fault

any excessive play in wheel bearings front or rear can cause ABS fault light to illuminate

 

JASONGDS
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Re: Where is the instrument cluster ground on a 463?

[quote=Pistonhead]

[quote=JASONGDS]

When you reset ABS by pressing the switch does it light stay on?

My ABS , over sensative, works fine until you come to a stop, then annoyingly kicks in, as if road bad surface, replaced a few sensors , and relay but to no avail, suggestions.....

[/quote

 

In your case Jason, I suspect your brake fluid renewal is much (if the fluid in your reservoir is dark or black in colour) overdue or the rear brake drums have excessive brake dust and, or may have hub oil leaking into the drum braking affecting the ABS.

It could be sensors too. Let m e do some digging and I will come back.

, Fluid changed regularly , 2 front sensors changed have ohm readings within tolerances, 1 rear sensor changed ( these annoyingly are handed and very expensive) re the front sensor should the inner ring ( with teeth on, located in the hub) should that be covered in grease? Or are my inner boots damaged?

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

REPLY TO THREAD No: 11

Hi Jason, 

 re the front sensor should the inner ring ( with teeth on, located in the hub) should that be covered in grease? Or are my inner boots damaged?

Grease in between the ring gear teeth should not be a problem; a cracked ring gear however, may. I am not sure now if a cracked ring gear shows an immediate ABS fault or manifests as over sensitive ABS application. There is a way to check for cracked ring gears and this shows up as a high peak pattern or as a break in pattern on an oscilloscope whilst the wheel is turned.

Please do check on the drums as I have suggested before.

It will be a few days before I can look into ABS for you and back on.

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Hi Guys,

 

Been a little distracted holidays and such.

Pistonhead YES please if you can put together a list of grounding points that would be great.

I have basically replaced almost every piece of the ABS system. 

Driving scenario: When I first turn the key ABS light illuminates (as it should). I start it up, ABS light goes out and then I can drive for a couple of blocks before the light comes back on shutting down the system. During this time when the light is out if I slam on the brakes the pulsing of the ABS is functioning properly. When the light goes on the ABS is off.

I can toggle the ABS switch off and on on my dash to reset it for another couple of blocks. 

Within that time period when the ABS is functioning when gently applying the brakes there is a one time slight shutter and softening in the pedal. But the brakes work as they should.

Through my research it is my understanding that within this initial time frame the ABS computer checks the sytem for errors bad sensors, low battery power, bad electrical connection, etc...

So I have come to the conclusion that there must be a bad ground somewhere. I could be wrong but I am running of options.

The fault code system on these first 1990 463s was a 3 pin plug in next to the battery that tells you things are not working. But nothing specific. At least not with the electrical test that I have.

I will review the grounding points that you guys have suggested. 

Any other help would be much appreciated.

Mark

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Pistonhead wrote:

Hi Mark,

My brother favours MAC's but it has limitations in the market.

I would suggest having the fault code read to point you in the right direction of diagnoses. I have located two more earthing points for you. One is by the steering coulomb, this is the earth point from the ABS switch. Is this in the engine compartment? since my drivers seat is on the left and yours is on the right are you referring to the right or the left side The ABS hydraulic pump has its own earth point by the pump. When I replaced the pump I made sure this ground was secure. There are a host of other earth points for each of the front, rear and center lock diff solenoids. 

I will make you a list of all the earth points but this will take time. I do not feel an earth point is your problem. How have come to decide this? 

You have mentioned that the ABS works fine for the first three hundred yards; I am assuming that the brake pedal pulsates under hard braking as per normal until after the three hundred yards. YES

Have you experienced any soft brake pedal on the first pedal application? And the pedal hardening on subsequent applications? YES

When was last the brake fluid was renewed? Is it dark in colour viewing through the reservoir? I have flushed over a gallon of MB brake fluid through the system trying to trach this down.

inkblotz
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Re: Where is the instrument cluster ground on a 463?

fixwin38 wrote:

hi Mark

ther are 12 grounding points on your G' (lhd) avery large cluster on front bulhead just below windscreen behind and to side of the instrument cluster Is this in the engine compartment or in the cab? I have pulled the instrument cluster and lower panel and cannot find a large grounding cluster. and some behind the earth connection to the battery another heavy duty cable  links the engine to the body under the footwell left or right footwell? also the buttons for the interion light switches in a major ground which affects the instrument cluster

ABS is doing exactly what is should to identify a fault

any excessive play in wheel bearings front or rear can cause ABS fault light to illuminate I have completely rebuilt both front wheels. new bearing and CV Joints which included the new ABS rings

 

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Hey guys any further suggestions/reponses to my replys to your posts.

I could really use your help.

Thanks

Mark

Pistonhead
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Re: Where is the instrument cluster ground on a 463?

Hi Mark,

Please furnish me with your full chassis number.

inkblotz
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Re: Where is the instrument cluster ground on a 463?

I have sent you my VIN. 

Thanks

Mark

inkblotz
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Re: Where is the instrument cluster ground on a 463?

When you guys speak of the grounding points behind the instrument cluster are you referring to your right hand drive Gs? Mine is Left hand drive and appears to have no grounding points there.

 

Thanks

Roly
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Re: Where is the instrument cluster ground on a 463?

Here are some pages from the MB manual on ABS testing.

Also a list of ground points from the later 463, couldn't find the early ones

inkblotz
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Re: Where is the instrument cluster ground on a 463?

Roly

​thanks very much. 

Hopefully I can put this to rest. 

 

Mark