rosros

I was just starting to trouble shoot cruise control not working when I saw this. The vacuum line is hard plastic and brittle dangling loose. The line is coming off the 'T' connector on one of the vacuum hose along the left fender feeding the cruise control. The line is between the brake master and fuse box. I do not see where the other end goes to. Meanwhile I put a toothpick into the line and wrapped in duct tape. Car is running and idling fine. No starting issues.

I also have the 'check engine lite' on. Went to Autozone and they scanned MAP sensor low circuit. Just had Goodyear replace the MAP sensor and associated pig wire on 11/28. The code Goodyear worked off of was P0107,P1107, P0300. After they replaced the sensor and wiring, codes cleared. Someone worked on it before and repaired the wiring instead of replacing pigtail.

Went back to Goodyear and they could not locate the vacuum leak that the code P0107 was putting out. Went to another shop and they had to smoke the engine. Some smoke came from the radiator area, but saw smoke coming out behind the battery. That is the general area the broken vacuum line was. Removed the cruise control, lt fender, and battery. Unwrapped the harnass next to the battery. Found the other section of the vacuum line. Also the battery vents have eaten away at the wiring harnass shielding and caused premature break in plastic vacuum line. Shop sealed the one side of the battery, siliconed the harnass assy and rewrapped the harnass. In the spring will have to remove the battery and spray paint the rails where the battery fumes lifted the paint.

So the 'T' connection is from the factory and goes into the main harnass. After the vacuum line was patched, the cruise control started to work again. Check engine light is still on, shop says it should cycle eventually and turn itself off. although car ran fine before the repairs, it seems to have an extra kick, the map sensor does not have to compensate for the vacuum leak. Nice to work with old school mechanic who knows how to troubleshoot.

engle1147

Not sure what year you 'vette is other than 90+ but I believe those vacuum lines should go to the cruise control and/or vacuum ball reservoirs.

aminnich

In the second picture you show the plastic line that goes off to the left, which goes into the harness and up to the vacuum ball. The line to the right goes to the cruise servo. I am not sure where the line off the top of the T fitting goes. The other line off the servo is usually a rubber line that goes thru the firewall to the switch on the brake pedal (and clutch if a manual trans). Possibly that line was spliced in the past with the plastic line you are holding?? From the PCM yours is either a 95 or 96, and I just looked at my 95 and see no other explanation for that line.

rosros

The plastic vacuum line comes off of the large harnass wrap, goes to the 'T" connector and a soft rubber vacuum line proceeds to the cruise servo connections closest to the firewall.


vacuum closest to firewall is where the 'T' connection hose is routed to.


overall view of the area where the 'T'connection is.

Having problems with the cruise control. Also having code for map sensor low circuit. shop replaced the map sensor and pigtail last week. Doesn't the map sensor have a vacuum line input?

aminnich

No vac hose to the MAP. Did you check the other hose off of the cruise control servo to see if it goes thru the firewall?

rosros

looks like the other hose goes to the firewall. it drops down from the cruise beneath the brake boost and disappears.

rosros

Updated posting. Shop found the vacuum leak.