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 and driveability. Bob
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 good. Hope your situation works out too...
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. BeeVee
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 make 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
49K 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 service"
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
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
TSB 91-10-6 FORD: 1988-91 CROWN VICTORIA, MUSTANG LINCOLN-MERCURY: 1988-90 TOWN CAR
1988-91 GRAND MARQUIS, MARK VII
ISSUE: 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.
ACTION: 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 details.
SERVICE PROCEDURE 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: NONE
SUPERSEDES:
90-21-5
WARRANTY STATUS: Eligible Under Basic Warranty Coverage, Emissions Warranty Coverage
OPERATION DESCRIPTION TIME
911006A Install Jumper Wiring Assemblies And Tie Straps 0.9 Hr.
DEALER CODING BASIC PART NO. CONDITION CODE
12A581 44
OASIS CODES:
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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