Hi everyone.
After I changed the front pads, (only) the brake light comes on when I apply the brakes. Before I compressed the brake piston, I removed the reservoir cap. Was I supposed to turn on the ignition? Did I damage the accumulator? The brake feels weaker and spongier now. The pressure switch goes on every 2nd time. I replaced the OEM accumulator years ago with the ACDelco 25528382 unit. After the system is fully pressurized, ignition off, it takes 58 pedal presses until it goes hard.
What other tests can I do?
Thank you.
I do not believe you can damage your accumulator merely by changing your brake pads. I see no connection.
On the '94 models the LF brake pad should be fitted with a wear sensor. Did you replace or refit the sensor when you installed the new brake pads? The brake warning light will illuminate when the brakes are applied if (a) the pads are worn to the point the sensor contacts the rotor thus electrically grounding the sensor (this should obviously NOT be the case with new pads and a properly fitted sensor), or (b) the sensor itself is worn through or a wire is broken creating an open.circuit.
One of the puny light gauge wires in.the pigtail that connects the wear sensor to the body wiring harness in my car broke; initially (I assume as that wire was beginning to break) I was getting an intermittent / flickering warning light as I applied the brakes; that eventually became a steadily on warning light every time I applied the brakes at which time I investigated and found the broken wire.
I*m guessing you removed the reservoir cap to prevent fluid from spilling out of the top when you retracted the caliper pistons. This is not a good practice. When changing pads on modern ABS cars is it always advisable to open the caliper bleed screws and expel the fluid there. Reverse flow of fluid in the system is an invitation to forcing contaminated fluid back into the VERY sensitive valves in the ABS block. In fact it is not a bad idea when changing pads to also flush the brake fluid and add new.
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Mike, thanks for the advice. The brake light was intermittent yesterday, now it comes on every time I press the pedal. I’ll check the sensor. I didn’t replace it but noticed the edge of the rotor cut a groove in it. I’ll take a closer look.
John, I removed the reservoir cap so the fluid can rise when I compressed the pistons. Now the fluid level is almost at the max. But its definitely time for a brake flush.
I forgot to mention, I bought Akebono pads (for the first time). I had OEM before. Maybe that’s why I feel the braking is softer/spongier.
It may need a good bedding in, I take it you simply replaced the pads without doing any work to the rotors, (scim or replace). If thats the case then it can take a while for the pads to take the shape of the surface of the rotor so basically you are compressing the pad surface to accomodate the surface shape of the rotor.
As has been stated, NEVER push fluid back into the system on ABS equipped cars,
I ordered new front rotors too and I’m going to do a brake flush.
Hi Joe, Did you disconnect the wear sensor lead at the plug when you changed the pads ?
One time when I changed the pads on my 94 Sovereign I had the ‘pads’ light come on. I found it was the pins on the two pin plug not making a decent connection with the socket. I think the sockets swell a bit and the pins don’t touch the sides. The holes are too small to get anything in them to clean them so I inserted a couple of strands of wire down the holes and then pressed the two halves of the plug together, it worked and the ‘Pads’ light went off. My brake pedal also felt spongy for the first hundred miles or so then firmed up an felt fine, this is common if you change only the pads and not the rotors for the reason Robin mentions ( bedding in )
At the time I too was worried I had damaged the ABS block because I did not open the bleed nipples when I forced the pistons back. I spoke to a Jaguar specialist ( David Marks he is the technical advisor for XJ40’s with the JEC and runs his own well respected Independant Jaguar workshop ) and he said not to worry. The brake fluid should not be any dirtier at the calipers than anywhere else in the system and is constantly circulating around and passing through the abs block so it’s highly unlikely I’d damaged it by doing that. He went on to say that they NEVER open the bleed nipples when changing pads on xj40’s or any Jaguar and they had never had a problem doing it like this.
Disconnect the sensor pigtail from the wiring harness and check that you have continuity through the sensor. If not, either a wire is broken or the sensor is broken. If you have continuity through the sensor, check for continuity between each sensor wire and ground, there should be none. These tests are, of course, without the foot brake applied.
Casso, Mike, thanks for the reply. I ordered new front and rear sensors, front rotors, rear pads and ATE brake fluid for flushing the old one out. This wasn’t the first time doing the brake job and I always used a C clamp to press the piston so the new pads would fit. But this is the first time the brake light comes on when breaking. I’ll take a closer look at the current wear sensors after changing them.
Did the same - no issues.
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It turned out I didn’t plug in the old pad sensor at the left front wheel correctly. I’m done with the front brakes, new pads, rotors, sensor, complete fluid flush and it’s all good now. I have just one question. Years ago I used silicone brake lube and it made the front caliper pin slider bushings swell. So I had to replace the front ones. They were so swollen on the front left side, the caps fell out. Has this ever happened to someone?
Nope, that is one way I have NOT tried to shoot myself in the foot.
Thanks Mike. This time I used a CRC synthetic lube.