Z_lover

The cruise control on my '81 280ZXT is not functioning. The "ON" light and "CRUISE" light will both illuminate on the control panel, but the speed is not actually set. I followed the troubleshooting guide per the service manual for this issue, testing the solenoid valve, servo valve, and actuator. They all functioned correctly. I suspect the inhibitor relay is bad, but wondering if anyone else has had a problem similar to this. I also found it odd that my car lacks a plug or relay for the slot labeled "Vacuum pump relay" on my service manual. I will admit that my service manual is for an '82. Any help is appreciated!!

280zx2by2

go down to the pedals and see it the brake pedals are missing this little plastic pieces, theres one that engages the brakelight and one that disangages the cruise

theres also one on the clutch pedal that disangages the cruise

sorry, its hard to explain, the only reason i know this is one day my brakelight wouldnt go out

let me take a pic right quick

theres a cover over it so i cant get a pic, did you check the vacum lines?

Z_lover

I haven't had a chance to look, but wouldn't my "ON" light not stay on if this switch was the culprit?

xenonxiii

You can get the 81 manual now on my site. Just got it done tonight.

Mike Brewington

first thing to check is the rubber pads that your swithces contact! Actualy cost about $2.00 a piece there are three of them part number 46512-H0101. You may have noticed a couple of little cacked pieces of plactic on you drivers side floor mat. Good luck very easy fix!

dustin_ra

Ive had the same issue except for mine does set but only after a few attempts. Pain in the **** but eventually I do get it to set.

Z_lover

So you continually hit the set button and it eventually sticks? Have you attempted to troubleshoot it or just live with it?

Z_lover

Thank you so much for posting the 81 manuals on your site!! These will be greatly appreciated.

davidjoe007

Thanks for the part number mike. I just ordered the rubber stopper because mine was gone. The part number for the rubber stopper on the brake is Nissan part number #46584-S0100. here is a link to good photos of the stoppers and the switches. http://z31.com/repairs/brakepedal/

BlueKitsune

Mine did the same exact thing, then I found a small tear in the little vacuum line for the cruse control, I replace the line, problem fixed! The little port on the manifold might be clogged too.

Uh semi related question, What speed do you have to be going at for it to even kick on? mine seems to not want to even turn on. well its says Cruise but never says ON.

NismoPick

I can't remember if it's 25 or 35mph... something like that is the minimum for cc.

BlueKitsune

Huh, my CC must have broken then as it wont even work at 45 MPH

davidjoe007

Well my cruise control is working again. I picked up and installed the little rubber stopper attached to the top of the clutch petal, and the CC works perfectly. I knew it wasn't a vacuum line because I had replaced every single vacuum hose under the hood. Anyways thanks for all the help everyone.

Z_lover

How did you locate the tear in the vacuum line or find a clogged manifold?

I am guessing that is where the issue is at because my interior display shows both the "Cruise" light and the "On" light when I set it. I would think that if the brake switch is bad, it would not electrically allow me to set my cruise and display the "On" light.

BlueKitsune

The tear was easy, I just looked over the line carefully, my manifold wasn't plugged but I bet you could use a small nail or something and poke out the carbon.
If both lights are on then you do have a vacuum leak I'm betting

etronsusie

Just joined Z club today & already rewarded. Used my book & checked everything I could to fix Cruise. Read about the clutch & brake stoppers, used tape to make test & presto cruise worked. Will order parts tomorrow. Thanks for the post.