77 to 87 Cruise Control Brain - Rebuilt
That was for the sticker! 
05-20-2015, 09:45 AM
#17
Rennlist Member
Great timing. My cruise has been a bit wonky lately. I was going to go through the trouble shooting procedure soon, but if it is the CC brain, this is great news! Thanks Roger!
05-20-2015, 10:04 AM
#18
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Thanks guys - so far we are 18 for 18 with zero issues. I swapped one into Zane's 87 and wow what a difference - very precise.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
06-02-2015, 11:39 PM
#21
Rennlist Member
Well, it wasn't so easy for me. The 86.5 hasn't had CC in the 20 years I've owned it, so I was excited, but it seems to have other issues that a rebuilt brain didn't fix. I tested Roger's rebuilt in the 82 and it works fine, so something else going on. I have vacuum going to the actuator, the reservoir holds vacuum, the actuator loses vacuum very slowly, not sure if that would be an issue or not. Could have just been the connection on the MightVac.
Fuse 4 is good. I hear a faint click when I engage the CC but nothing happens, no setting and no accelerating.
Years ago I tried to do the troubleshooting steps and there's a step where you jump two posts on the plug to the brain, and something is supposed to happen, but everytime I tried that it blew fuse 4. Never could figure out why. The goal is to get it working by next week for a 3000+ mile roadtrip my son and I are taking. At least I have plenty of working parts to swap out from other cars. Might start a new thread but let me know if anyone has any ideas.
Fuse 4 is good. I hear a faint click when I engage the CC but nothing happens, no setting and no accelerating.
Years ago I tried to do the troubleshooting steps and there's a step where you jump two posts on the plug to the brain, and something is supposed to happen, but everytime I tried that it blew fuse 4. Never could figure out why. The goal is to get it working by next week for a 3000+ mile roadtrip my son and I are taking. At least I have plenty of working parts to swap out from other cars. Might start a new thread but let me know if anyone has any ideas.
06-05-2015, 12:27 AM
#23
Rennlist Member
I don't want to turn this into a thread about my CC problem, but here's what I have found so far - All WSM tests check out fine except the last one, the speed sensor. I slowly rolled the car in the garage with the Ohmmeter attached to pins 11 and 12 and it stayed at zero Ohms. I'm assuming this will keep the CC from working? I'll check the connection near the spare tire tomorrow. Speedo is working.
06-07-2015, 05:06 PM
#24
Rennlist Member
Got my CC fixed! I had a broken wire (speed sensor) at the CC brain plug. First time to have CC on the 86.5 in 20 years of ownership.
Last edited by Don Carter; 06-08-2015 at 12:24 AM.
10-01-2015, 01:27 AM
#26
Disappointed
Got my new (rebuilt) CC brain from Roger, and am having issues...
When I first plugged it in I was having the same issue I had with the last one near the very end, which was I couldn't get anything to happen. I checked all of the vacuum connections, the servo and everything seemed fine as there were no broken connections and the system was holding vacuum.
When I drove the car tonight, it would accelerate with the stalk held in, but not hold speed. Hitting resume would do nothing.
I had gotten the system previously (with the old brain) to work temporarily by trying the oven trick, which got all functions working. However it eventually devolved into not functioning at all. This new one appears to maybe evolving into maybe working????
When I first plugged it in I was having the same issue I had with the last one near the very end, which was I couldn't get anything to happen. I checked all of the vacuum connections, the servo and everything seemed fine as there were no broken connections and the system was holding vacuum.
When I drove the car tonight, it would accelerate with the stalk held in, but not hold speed. Hitting resume would do nothing.
I had gotten the system previously (with the old brain) to work temporarily by trying the oven trick, which got all functions working. However it eventually devolved into not functioning at all. This new one appears to maybe evolving into maybe working????
10-01-2015, 12:55 PM
#27
Rennlist Member
Got my new (rebuilt) CC brain from Roger, and am having issues...
When I first plugged it in I was having the same issue I had with the last one near the very end, which was I couldn't get anything to happen. I checked all of the vacuum connections, the servo and everything seemed fine as there were no broken connections and the system was holding vacuum.
When I drove the car tonight, it would accelerate with the stalk held in, but not hold speed. Hitting resume would do nothing.
I had gotten the system previously (with the old brain) to work temporarily by trying the oven trick, which got all functions working. However it eventually devolved into not functioning at all. This new one appears to maybe evolving into maybe working????
When I first plugged it in I was having the same issue I had with the last one near the very end, which was I couldn't get anything to happen. I checked all of the vacuum connections, the servo and everything seemed fine as there were no broken connections and the system was holding vacuum.
When I drove the car tonight, it would accelerate with the stalk held in, but not hold speed. Hitting resume would do nothing.
I had gotten the system previously (with the old brain) to work temporarily by trying the oven trick, which got all functions working. However it eventually devolved into not functioning at all. This new one appears to maybe evolving into maybe working????
