Chevy pickup relay clicking with brake pedal

[JHZR2]

98 S-10 ZR2, 65k. Everything runs beautifully.

Only when in park, sitting stationary, as I push the brake pedal down or let up, I hear a relay click and then release. Over and over (sounds confused).

No matter how much I diagnose, I can't seem to get it to do it any other way but in park.

No other issues, no lights, abs perfect, lights go on and stay on, etc.

But it never did this before.

 

[NHGUY]

Brake/shift interlock?

 

[ls1mike]

Sounds like the neutral park safety switch.

 

[cb_13]

Originally Posted By: NHGUY
Brake/shift interlock?

That's my guess as well. The interlock solenoid on my Ford Escort was loud enough to be noticeable.

 

[Doog]

My 99 Suburban did that until I was almost committed to a mental institution from hearing it on a 1400 mile trip to Florida. I had a GM dealer repair it in Florida. I think it was the brake light switch which also is the safety switch IIRC. The repair was replacing the switch. Mine did it every time you touched the pedal. Just loud enough to hear.

 

[Pop_Rivit]

It should be simple enough to diagnose, especially since it only does it while in park.

Just grab your mechanics stethoscope and have someone press on the brake pedal while you kneel at the door and with the probe listen for what's causing the noise. Once you identify the cause it should be an easy fix.

 

[crazyoildude]

+ 1

 

[JHZR2]

It is related to the shift interlock since I can feel some faint remnant of the "click" in the selector handle.

I guess what I should have phrased is should I be concerned?

Here's the deal: no issues ever with going in and out of park. But with the pedal depressed, especially if it stays depressed with a change in the pedal position, the relay clicks over and over.


This didn't used to be the case.

It only happens with the selector in park.

So should I be concerned? The fact that this behavior only started recently is what bothers me.

Main concern is it stranding me due to being stuck in the wrong condition, or a malfunctioning relay/switch causing an intermittent parasitic drain.

 

[JHZR2]

Originally Posted By: ls1mike
Sounds like the neutral park safety switch.


Odd thing is that I've absolutely verified that it never occurs with the selector in neutral.

 

[anonobomber]

Originally Posted By: JHZR2
Originally Posted By: ls1mike
Sounds like the neutral park safety switch.


Odd thing is that I've absolutely verified that it never occurs with the selector in neutral.


That's because it only is supposed to lock when in the Park position. If it locked in any other position that could be really bad.

 

[01rangerxl]

Originally Posted By: JHZR2
It is related to the shift interlock since I can feel some faint remnant of the "click" in the selector handle.

I guess what I should have phrased is should I be concerned?

Here's the deal: no issues ever with going in and out of park. But with the pedal depressed, especially if it stays depressed with a change in the pedal position, the relay clicks over and over.


This didn't used to be the case.

It only happens with the selector in park.

So should I be concerned? The fact that this behavior only started recently is what bothers me.

Main concern is it stranding me due to being stuck in the wrong condition, or a malfunctioning relay/switch causing an intermittent parasitic drain.



Hopefully it's just the brake lamp switch confusing the BCM and as a result the shift interlock solenoid. The brake lamp switch is $10, no big deal. If your brake lights weren't working, this part would be the obvious culprit.

But with your brake lights coming on, it may not be. The signal from the brake lamp switch goes to the body control module, which then turns off the lock solenoid in the column, releasing the lever.

GM BCMs from the 1990s to pretty much now aren't the most robust things. The S-Series doesn't seem as problematic as some models, but there are Impala BCMs we keep in stock at work.

The solenoid in the column can go bad too, and would be the source of the click you feel in the shifter handle...but it is obviously releasing like it is supposed to, so I think it is more likely that the solenoid is getting a bad/confusing signal rather than having a problem itself.

I'd start with the brake lamp switch since it's cheap and easy. Throw the old one in the glovebox as a spare. If that doesn't do it, there may be emerging issues with the BCM. Pretty much impossible to say if/when it will cause it to get stuck in park. It may keep doing what it's doing now the rest of the time you have the truck with no additional symptoms, or the next time you drive it, it won't come out of park. With the engine off, and column unlocked, you should be able to get it into neutral, then start it up and shift into gear to get where you need to go.

 

[01rangerxl]

There should also be a BTSI relay in the underhood fuse box. It's not making the noise you are hearing, but maybe it's acting up and the solenoid is going nuts as a result.

 

[supton]

How hard is it to just remove the brake-shift interlock? I never card for them, and if the BCM is having issues, with just this feature--maybe the feature can just be removed and avoid replacing the BCM.

 

[Silverado12]

FWIW I've had relays go bad and they will intermittently or continuously click like what yours is doing.

 

[01rangerxl]

Originally Posted By: supton
How hard is it to just remove the brake-shift interlock? I never card for them, and if the BCM is having issues, with just this feature--maybe the feature can just be removed and avoid replacing the BCM.


Might be worth a shot to unplug the wire to it and see what happens. It shouldn't lock the lever if it doesn't have power to it. That will require taking the covers off the column.