Car: 1989 Mercury G/M w/43k miles
Code 31 is EVP or PFE circuit below minimum voltage.
Cleaned, inspected EGR valve and replaced EVP with no change. Long story
short, the problem appears to be at the 10 pin cylindrical shaped
connector C388 (for those with a wiring diagram) located at the top rear
of engine beside the upper intake. The CEL will consistantly illuminate
on, then off, when wiggling the connector and/or associated harness. The
other connector at the EVP end appears OK since wiggling has no effect on
the CEL. Sooo, since the harness is NLA from Ford, I will try inspecting
this connector (C388). Has anyone had any experience disassembling the
connector right down to the individual wires. Can it be done with the
correct pin extraction tool or something equivalent. I have already
reseated the connector with no change and have a feeling it could (1), be
a bad crimp, (2), a female connector pin in need of tensioning or (3),
broken intermittent harness wire. It also makes me suspicious on the
condition of the remaining wires associated with this connector, not to
mention its brother 10 pin connector (C386) mounted right beside it. One
would have to wonder the best way a dealership would tackle this problem
without a replacement part available.
Please respond here and not my email address. Any input appreciated.
Look at my message above called "Crap in Electrical connector".
I just got done cleaning all the crap out with some tuner/contact cleaner
and a drill bit small than the pin(careful not to get a bit too big and
scrape up the sockets). Lots of solidified crap came out. So far it runs
smooth with no codes. I guess at some point i should get some of the
dielectric grease for it but for the time being I'm going to monitor codes
PS I called the ford dealer and they do put dielectric grease in there to
keep out corrosion etc. I speculate the grease hardens over many years and
through vibration, expansion and contraction, etc actually forms a insultive
barier between the pin and socket when it stiffens. The crap I pulled out
was pale greenish tan, some brown and pretty stiff/coalugated.
I was already aware of the dielectric grease applied from the factory. I'm
planning on spraying some DeoxIT D5 cleaner on the pins, clean out the
residual and go from there. Maybe a pipe cleaner, compressed air and D5
contact cleaner would work. I'm also interested with anyone who has
attempted the extraction of the connector pins for a closer visual
inspection noting faulty pin tension or crimps etc. Since many actuator
circuit wires bottleneck at these two connectors, there's the potential
for alot of intermittent problems espesially with an older car. Maybe we
should call it "Malfunction Junction".
The weather here on the east coast got down to single digits, so it will
be a while before I attempt to further evaluate the situation. Until then,
I'm seeking advice from those who have experienced problems possibly due
to this connector and what the repair action was to rid the problem for
Hope your situation works out too...
Have not tried that and it may be a few days before I can. Would loosing
vref and feedback (both wires open circuit) by disconnecting EVP cause the
ECC to give an error code 34 under normal conditions???
Yes. A 31 indicates the voltage lower than expected. By disconnecting the
connector Voltage goes high ( open circuit ), so the processor will give a code
34 for a higher than expected voltage. That does not mean that there is an
electrical fault. It could be that the push rod and seat of the EVP has worn so
is shorter giving a few tenths of a volt lower than normal. The same thing can
happen with the EGR valve pintle. It over time may have worn in its bore, so
when it closes goes deeper into it, having the same result, a lower than
expected voltage when closed.
Hi Mike, Yes a few years ago I had a 92 CV with a harness problem. Ford
would not honor the wiring recall
and fix the car for free. So Like you, I did a 1 for 1 wire connection and
rid my problems elimination all the
factory connectors under the hood. Be aware some of the connectors will
change wire color as it crosses
the coupling. I just cut the wires and soldered them together with stakon
wire connectors and shrink wrapped
all of the wires and did final shrink wrap over the whole bundle. I have no
faith what so ever in fords
connectors. I never had another problem again after that.
The car of your's is so aged as it will have no effect to the resale value.
Sorry, It was a couple years ago, I didn't persue ford for it, just no
longer pay prime
dollars for their cars. I now buy them way below market for that reason.
However I found mention of the notice here. But as I stated Ford will not
good on their recall. Now I have a 98 CVLX with bad intake and I know Ford
won't make good on it either, so at auction I paid $ 5ooo. for a car with
miles on it. Just as now that U haul has banned explorer from tow behinds
they are only worth half of the book value or less at auction.
recall info here
Yeah, I did notice under the TSBs, there were a couple titled:
"Wire Harness - Terminal Repair Kit" and "New terminal grease released for
I think what I may do first is pick the Ford/Mercury parts departments's
brains concerning any wire harness repair kits and if they were applicable
to this problem. I'm sure there's quite a history to this. This BTW is my
father's Mercury which he bought used in 1991 w/13k miles and the problem
was already happening. He transferred the warranty after purchasing the
car. He had the car looked at by a Mercury dealership (under warranty)
back then and they replaced the EGR valve, EVP sensor and EGR solenoid,
which seem to fix the problem for a while. The problem has come back and
very intermittent. After doing a google search for similar problems, I
decided to do the wiggle test (as someone else had done) and sure enough,
the CEL came on and off on my command by moving the connector/harness one
way to turn on the CEL and moving the opposite direction turning CEL
off...So there ya go. I don't want him spending lots of money at the
dealership for parts not necessarily needed. I also noticed when wiggling
the connector/harness the engine (which has always idled smoothly) missed
and almost stalled, so there's probably other wires to other actuators
junctioning here that are potential problems waiting to happen. I'm not
sure I would want to bypass the connector and hardwire. I'll first check
with the parts and service departments this week if time permits and
hopefully get a history backround to these wire harness problems and the
correct repair action...Thanks
FORD: 1981-99 ESCORT
1983-99 CROWN VICTORIA
LINCOLN-MERCURY: 1983-99 CONTINENTAL, GRAND MARQUIS
1988-92 MARK VII
1993-98 MARK VIII
1996-97 COUGAR, TOWN CAR
MERKUR: 1985-88 XR4TI
LIGHT TRUCK: 1981-96 BRONCO
1981-97 F SUPER DUTY, F-250 HD, F-350
1981-99 ECONOLINE, F-150, F-250 LD
1984-90 BRONCO II
1997-99 EXPEDITION, MOUNTAINEER
1999 SUPER DUTY F SERIES
MEDIUM/HEAVY TRUCK: 1984-99 F & B SERIES
1988-97 CARGO SERIES
1996-98 AEROMAX, LOUISVILLE
Ford Motor Company has released a new Electrical Grease (F8AZ-19G208-AA) to
reduce the possibility of moisture corrosion at the terminals.
Add the new grease during electrical connection repair.
CAUTION: ELECTRICAL CONNECTOR GREASE SHOULD NOT BE USED IN HIGH VOLTAGE
CONNECTIONS FOR SPARK PLUG AND COIL WIRE APPLICATIONS.
PROPER USES OF THE NEW ELECTRICAL GREASE INCLUDE:
DO NOT USE ON:
Spark Plug Wires
Spark Plug-to-Coil Connections
Low Current Flow Switches (12V Systems less than 0.1 amp)
OTHER APPLICABLE ARTICLES:
201000, 201100, 201200, 202000, 203000, 203200, 204000, 205000, 601300
FORD: 1988-91 CROWN VICTORIA, MUSTANG
LINCOLN-MERCURY: 1988-90 TOWN CAR
1988-91 GRAND MARQUIS, MARK VII
An intermittent high idle, a MIL light that comes on or EEC Service Codes 31 or
32 appearing may be caused by a loose connection of the wiring to EVP (EGR),
TPS, ACT, ISC, CP, Knock Sensor or Injectors. The 10 way connector is located at
the top rear of the intake manifold.
Inspect the 10 way connector for loose connections. If necessary, install two
(2) new jumper wiring assemblies which provide for better connections and more
slack in the wiring harness. Refer to the following procedure for service
Identify the sensor causing the concern.
Locate the appropriate 10 way connector, Figure 1.
Figure 1 - Article 91-10-6
Separate both connectors.
Carefully mate the new added jumpers (F1ZZ-12K510-A and F1ZZ-12K510-B) to the
proper terminals as shown in Figure 2.
Figure 2 - Article 91-10-6
Make sure the wires do not touch the hot EGR valve.
Use two (2) tie straps (95873-S) to secure the jumpers to the A/C suction hose.
If the vehicle is non-A/C, attach the jumpers to the existing 12A581 wiring
assembly at the dash panel.
Make sure that the connectors have been fully mated and are completely locked.
Check the vehicle for proper operation.
PART NUMBER PART NAME
F1ZZ-12K510-A Jumper Wiring Assy.
F1ZZ-12K510-B Jumper Wiring Assy.
95873-S Tie Strap
OTHER APPLICABLE ARTICLES:
Eligible Under Basic Warranty Coverage, Emissions Warranty Coverage
OPERATION DESCRIPTION TIME
911006A Install Jumper Wiring Assemblies And Tie Straps 0.9 Hr.
BASIC PART NO. CONDITION CODE
203000, 203200, 206000, 619400
If the harness has slack in it, the connector is most likely not at fault.
to check if the connectors are making contact or not(inside the
connector block), do this: i use sewing needles, or pins, the kind with
a plastic head on them works pretty good.. i put one pin on one side of
the connector right into the wire and then the other pin on the
adjoining wire on the other side of the connector... then put a meter on
the two pins..should be getting continuity unless the pins inside are
bad.. also one [pin into the wire and then the meter to the sewing pin
and then to the pin of the connector.. looking for a break in the
circuit.... hope this helps.
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