I found the problem with the cruise control in my wife’s 1990 XJ-S
convertible (5.3L V12) yesterday. The cruise control started to be
intermittent a few months ago and hasn’t worked for the past few weeks.
I checked the vacuum lines going from the front of the right side intake
manifold to the cruise control bellows and noticed that one of the small
plastic nipples had broken completely off of the Solenoid Valve (EAC 7935)
cutting off the vacuum source to the cruise control. I left the broken
solenoid valve in place, connected the vacuum line from the intake manifold
directly to the cruise control bellows, and then verified during a drive
that the cruise control works properly again. Now I would like to find a
replacement for the EAC7935.
I looked through the archives and found a lot of folks discovered their
EAC7935 was also broken but I couldn’t find a source of a replacement part.
I called the parts department of the local Jaguar dealership this morning
and verified that EAC7935 is No Longer Available through them.
I understand that the EAC7935 is part of this cars vacuum advance control
system and would prefer not to have it permanently disabled. What is a
suitable replacement for the EAC7935 and where can I get one?
Regards,
Paul M. Novak
1990 Series III V12 Vanden Plas
1990 XJ-S Classic Collection convertible
1987 XJ6 Vanden Plas
1984 XJ6 Vanden Plas
1969 E-Type FHC
1957 MK VIII Saloon
Ramona, CA P.M.Novak7@gmail.com
In reply to a message from Paul M. Novak sent Mon 16 Nov 2015:
How is it part of the advance system. 1990 would be
marelli with a dedicated vacuum line to the ecu for timing
function. I thought the solonoiod valve was just there as
a safety dump valve for cruise control.–
The original message included these comments:
I understand that the EAC7935 is part of this cars vacuum advance control
system and would prefer not to have it permanently disabled. What is a
Hope this helps.
Steve–
The original message included these comments:
How is it part of the advance system. 1990 would be
marelli with a dedicated vacuum line to the ecu for timing
function. I thought the solonoiod valve was just there as
a safety dump valve for cruise control.
Thank you for your response. I was wondering the same thing about that
solenoid valve. It is listed in the Jaguar XJ-S Parts Catalogue under the
section for vacuum advance, but that really didn’t make sense to me based on
it’s location and connections in a Marelli car. It is not listed in the
parts catalogue under the Cruise Control, but based on your email I reviewed
the S-57 Electrical Guide and I can see a “Solenoid Vacuum Valve” on the
Figure 20.1 wiring diagram, but it isn’t shown on the Figure 20.2 equipment
layout picture. The valve has two ports with a vacuum line from the front
of the right hand intake manifold going to one port and a vacuum line from
the cruise control bellows going to the second.
I have more work to do on that car before I solve this and some other
related issues, but for now I plan to leave that valve in place and
disconnected from vacuum until I can find a suitable replacement, which may
be a generic solenoid valve as was suggested in another reply by Ed Sowell.
From the Cruise Control wiring diagram in the S-57 Electrical Guide, you
appear to be right that it is a safety dump for cruise control vacuum just
in case the brake switch doesn’t kill the vacuum at the cruise control
solenoids. However, I think that solenoid may also serve a function to
avoid vacuum leaks at the cruise control assembly from affecting things like
overrun fueling problems on cold start. Which is why I have been working in
that area because I have that overrun cycling issue on cold start in my
wife’s 1990 XJ-S convertible and I am working through the vacuum trying to
find the leak. But that will be covered in other postings as I continue to
track down the source of that problem.
Regards,
Paul M. Novak
1990 Series III V12 Vanden Plas
1990 XJ-S Classic Collection convertible
1987 XJ6 Vanden Plas
1984 XJ6 Vanden Plas
1969 E-Type FHC
1957 MK VIII Saloon
Ramona, CA
P.M.Novak7@gmail.com-----Original Message-----
From: owner-xj-s@jag-lovers.org [mailto:owner-xj-s@jag-lovers.org] On Behalf
Of baxtor
Sent: Monday, November 16, 2015 11:47 AM
To: xj-s@jag-lovers.org
Subject: Re: [xj-s] Cruise control fixed but where can I get a EAC7935
solenoid valve
In reply to a message from Paul M. Novak sent Mon 16 Nov 2015:
How is it part of the advance system. 1990 would be marelli with a dedicated
vacuum line to the ecu for timing function. I thought the solonoiod valve
was just there as a safety dump valve for cruise control.
The original message included these comments:
I understand that the EAC7935 is part of this cars vacuum advance
control system and would prefer not to have it permanently disabled.
What is a