I have learned that the wiper motor is connected to negative distribution terminal 158 which in turn connects with earthing point 7 under the radiator. Could anyone instruct me as the how to check and clean these connections? Thanks

 

basically, disconnect your battery's negative terminal, unbolt the earth point, clean with steel wool and reassemble

also, check for any damage to wires and repair as necessary.

the ground that you are looking for is most easily located when standing on the right side of the car, looking down past the battery, below the radiator. it is a few inches towards the center of the car from the radiator drain plug.

 

Thanks, Car Nut. I have located all of this. Let me ask you this. My wipers cause the engine to stall when they are turned on. But if I pull them away from the windshield the engine keeps going. So...when they need just the amount of extra power to overcome the windshield's friction,... poof. Any theory about what is going on? I don't understand, I confess, how an earthing connection could effect the electrical system in this manner.

 

Hankster,
The earthing point below the radiator caused me some problems, which I fixed by re-terminating all the wires with new 'eye' connectors and soldered them rather than crimping. Be careful as all the wires are only just long enough, if they have already snapped - some of mine just fell away from the termination!
The reason the wipers are causing the engine to cut out is that this earting point does the wipers, the indicators, various engine functions and more. As the connection is so poor, it can probably pass just enough current with the engine running and the without the wipers on load. When you put the wipers onto the screen, the load increases (the wipers need more current) and that current has to try to flow through the same earth point.

If there is resistance in the connection (poor earth) then there will be a potential difference (voltage difference) between the terminal and earth, as the current has to run through effectively a further resistor. So, instead of your engine management system working on 12V, it may find itself trying to work of 10V, or less, and not being able to work of that voltage. Another way of looking at it is that the engine electricals require only a relatively small current to flow. This may pass through the earth connection OK but if the current from the wiper motor has to go through there also, it may be that this limits the current flowing from the engine electrical too much and causes the cut-out.
HTH

 

Originally posted by Hankster:
[qb]Couldone  some tell me where the earthing point on the front crossmember of my 85' Saab is located?  If you could direct me to a diagram or picture that would be great. My wipers cause the engine to stall.  Thanks, Hank [/qb][/b]

It's under the right hand side of the radiator near where the battery sits. In my 1983 900S there is a large braid and lots of other earth wires from various places around the engine connecting to it. Probably a wise idea to completely renew or at least clean it now and then to ensure the electrical contact between the chassis and the braid, etc. are maintained.

Regards,

Craig.

 

Originally posted by xassh:
[qb]basically, disconnect your battery's negative terminal, unbolt the earth point, clean with steel wool and reassemble

also, check for any damage to wires and repair as necessary.

the ground that you are looking for is most easily located when standing on the right side of the car, looking down past the battery, below the radiator. it is a few inches towards the center of the car from the radiator drain plug. [/qb][/b]

In addition to steel-wool, clean all the grease and oil away from the surfaces which will make the electrical connections using your choice of degreaser. Most people use WD40, RP7, or similar. Removing grease/oil helps ensure the contact resistance stays low for as long as possible but the earth points should be checked regularly but only need work if they give problems or show signs of corrosion.

Craig.

 

I would not use WD-40 as it has oil in it. Try brake cleaner, I like CRC in the green can (BUT in a well ventilated area! it's flammable!).

This should give a good dry oil/grease free surface to work with. AFTER you have made the new connection you could use a rust proof paint (get a bottle or can of rustolem) to put over the area to keep it stable.

let us know how you are doing!