R107 SL ABS Light not going on at all

[tristand]

Hi,

I'm looking at buying an SL420(R107). When I turned the ignition on I noticed that the ABS light did not come on at all. I believe it should come on to to indicate that it is functioning properly and then go off once the engine is started.

I would have expected that the ABS light stay on if there was a problem with any of the three sensors, or if the was a fault with either the ABS Relay or the ABS ECU.

Is the only case where the ABS will not go on be for the following reasons
* The bulb is gone/blown(Is this common?)
* The bulb has been removed

Is this a MOT failure, or will it depend on the tester?

 

[mct_cars]

Yes, Yes, and depends if it's noticed. Easy to change as the instrument binnacle isn't held in by anything. Just pull forward and shuffle from the top and sides.

Could be innocent, could be hiding a problem (the ABS unit isn't cheap). Other way is to stomp on brakes to see if the ABS actually works.

 

[tristand]

mmmm. after test driving, the owner took over driving and gave it a bit of welly. They also demonstrated the brakes by slamming on, albeit 35mph. The ABS didn't kick in as you would expect in a modern car. I was thinking that an older SL might not kick in as easily.. This is all pointing at an ABS fault, car is off the road, no tax, insurance or MOT. I asked the owner if they were willing to put it through the MOT, response was, they could but would increase the price of the car.

Do you know the range of cost it would be to fix this problem, from a replacement relay, to all sensors and ABS ECU?

I've seen the ABS sensors at around £150 a pop!

 

[notsofast]

Usually the most susceptible component are the wheel sensors as the cables flex to accommodate wheel movement. Dashboard bulbs are far more reliable, a lot cheaper and usually the cheapest way to disguise a fault. There are even unscrupulous individuals who hard wire the ABS bulb with a delay relay to make it appear that all is well to the MOT tester or unsuspecting buyer rather than fix the real issue.
ABS sensors r107 abs sensor | eBay

 

[tristand]

I plan to check the bulb then the sensor resistances with a multi meter to establish if any of the sensors are at fault.

Given the possibility that the issue was deliberately masked and the potential cost to get sorted and through the MOT, would it be reasonable to knock 800-1000 off the asking price?

 

[notsofast]

With all due respect, ABS is pretty fixable as most parts can be found and fairly easily installed. But before you part with your cash, I would be a lot more wary of other fast fixes such as thick engine oil to silence a rattly engine and other "mechanic in a bottle" solutions (gearbox / diff). Also have a very close inspection at the body work and underside for hidden rot. These things can be a lot more expensive to fix.
I am speaking from experience as I am a past expert at purchasing tarted up heaps of junk. By choice I would rather buy a car with all of its warts on display than anything with fresh paint or smelling of underseal. If the rest of the car checks out then be brave with your bargaining. The worst the vendor can really say is no. Summer is coming to an end so there will be less of a queue at his door for a drop top.