slow cranking and parking brake cable smokes

[jlprice]

I thought I remembered a discussion of this, but searching has not turned it up. Occasionally, my 97 Disco cranks very slowly and I notice smoke coming out of the parking brake cable. I noticed after I did the engine swap that the parking brake was seized and just assumed I had damaged it. I am wondering now if it was the same problem. It seems like the starter is using the Parking brake cable as a ground and burning up the cable. I have already run stainless braid from the battery grounding point to the starter housing and then up to a second point on the block. I have replaced both battery cables.

Has anyone seen this before? If so, what causes or cures have you found?

thanks in advance
-jeff

 

[edthediscoman]

I have to assume that the battery is grounded to the frame somewhere, and that that cable is good. Antther thing to check, is if you remove the negative from the battery terminal (assuming you know your radio code), shut all electrics off, and then check for potential difference from the negative lead to the negative terminal. This will tell you if there is a drain somewhere that is lowering the battery power while off, and maybe when needing max amps, creating a short. If there is any voltage at all (should only be for your clock - so very very low - or you can remove the clock and there should really be none - doors closed etc.) Then - if you believe it may be grounding to the brake cable (which I have never heard of), follow the cable and look for a hot wire that may be chaffed against it. Not sure but i think the heated seat wires, the window wires etc run near it....esp at the end where its attached to the brake handle.
Not sure if the window wires are hot when you start, but if they are shorting while the car is on, one of those items may be slow/not working.
Just an idea.
Not sure if it will help any, but I have had tons-o-fun chasing wiring on my Triumph over the years, so I know anything is possible!!
Ed

 

[ShaunP]

Bad earth, most likly engine to chassis.

 

[Rocky]

You are right that the parking brake is being used as a ground.

Remove all the ground cables between battery/chassis/engine/starter clean up the connections and reinstall.

 

[jlprice]

Thanks guys, I haven't checked the battery voltage, but I have a dual battery setup with hell roaring isolator and the Optima red-tops are only six monthes old so I was betting they were a low probability. The battery cables (red and black) are brand new landrover parts (that could be the problem ) and when I installed the negative lead I pulled a piece of stainless braid from the negative earthing contact of the battery to the starter and then up onto the top of the bellhousing.

So it seems like I must have a good ground and yet I don't
Most puzzling, and yesterday it started right up going to work and coming home. Assuming the stainless isn't some exotic megohm freak, the only point where it could be hosed up is the interface where the battery neg lead grounds to the body and ties to the braid.

HMMMMM, maybe I'll take a file to that earthing point, put it back together with a copper bolt and nut and then swath the whole thing in di-electric grease. Anyone see any issues with this approach?

Are there any suggestions of good grounding fixes that have worked for you in the past? Thanks
-jeff

 

[RichardS]

Jeff from what you just wrote it sounds like you should have a good ground from the battery to the motor. But you did not mention the frame, that needs to be checked as well. The issue could be that current is trying to flow from your motor/trans, through the parking brake cable to the body/chassis. So give the chassis ground a good cleaning if you have not already done so.

 

[SuperJ]

Stainless is a good conductor of heat but a poor conductor of electricity. The same oxidation process that prevents it from corroding acts to electrically insulate it from terminals and fasteners over time. Replace with copper and all will be well. Clean the ground points smear on a layer of never-sieze (the copper based stuff works best for this) and tighten securely.

 

[frickjp]

Parking brake is mounted to the chassis on one end, engine on the other. What's missing is a decent chassis to engine ground. Negative terminal on D1 goes to the chassis, then on to the frame. Engine is grounded via a braided strap near the rear pass corner of the engine. A good setup is battery to chassis, chassis to frame, frame to engine. Inner wheelhouse right near the battery is where the factory ground goes.

 

[jlprice]

Actually stainless isn't a good conductor of heat either. I knew it wasn't nearly as good as copper, but hoped it was "good enough" but apparently not. I had a tuner grounding kit I had bought from Summit racing a while back. Honestly, I was holding off installing it because of the shiney blue color. It was the only color they had and it took three monthes to arrive.

BUT! It fixed the grounding problem, in a pretty easy clean install. I don't think the truck ever turned over so fast.

thanks for all the helpful input.
-jeff