How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Bosch2012 Your Own Question

Bosch2012
Bosch2012, Auto Mechanic
Category: Car
Satisfied Customers: 3
Experience:  Expert in diesel fuel injection machanical and electronic on vehicle fault finding
69552154
Type Your Car Question Here...
Bosch2012 is online now
A new question is answered every 9 seconds

Plymouth Voyager SE: I have a 1988 Plymouth Voyager SE, 3.0

Resolved Question:

I have a 1988 Plymouth Voyager SE, 3.0 Liters V6 Engine, FWD-3 Speed Auto Trans. (Model A670) and the situation is as follows: The Dealer replaced the ECU/SMEC unit back in 2004 and lately we are experiencing the Tachometer giving False RPM (goes to zero and up and down while idling and while driving on road and/or highway. I have replaced the Distributor and RPM-Tachometer but this did not cure/resolve the problem, so in my next step, I Disconnected the Battery and took it out of the vehicle and Cleaned all of the Electrical Connectors/Contact Points underhood and I found some to be very dirty (including the ECU/SMEC contacts) and applied Dielectric Silicone Compound). The RPM-Tachometer is reading a lot better/stable accurate reading now. Are there any other suggested tests and/or remedies that you can suggest?
Submitted: 2 years ago.
Category: Car
Expert:  Bosch2012 replied 2 years ago.

Bosch2012 :

Hi,

Bosch2012 :

If the terminals of the ECU were coroded, then the chances for the termanals in the plug connectors on the wiring harness connected to the ECU could be dirty/ damaged. i suggest you unplug the wiring harness connectors and clean them thoroughly. You can bend the lugs inside the connectors so they fit tighter onto the ECU terminals.

Customer: YOU, APPARENTLY DIDN'T READ OR FUULY UNDERSTAND MY DETAILED STATEMENT OF THE PROBLEM AND THE FACT THAT FULLY CLEANED ALL OF THE ELECTRICAL CONNECTIONS/CONTACTS UNDER THE HOOD (FROM FIREWALL TO ALL COOECTIONS) INCLUDING THE ECU/SMEC WITH "ZENEX-ZenCircuit II Contact Cleaner" and "DIECLECTRIC SILICONE COMPOUND" ON ALL OF THE ELECTRICAL CONTACTS CLEANED (I DID FIND SOME VERY DIRTY CONTACTS/CONNECTIONS AND I THORUGHLY CLEANED THEN! THE TACH. IS NOW
Customer: READING WITHOUT BOUNCING ALL-THE-PLACE/GIVING FALSE RPM READINGS. SO WHAT I WANTED TO KNOW WAS IF THERE WERE AND OTHER SUGGESTIONS THAT MAY HAVE OR COULD HAVE CAUSED MY SITUATION (PRINTED CIRCUIT, ETC.)
Customer: THANK YOU VERY MUCH, BUT YOUR ANSWER DOES NOT ADDRESS MY SITUATION.
Customer: PS AUTO CYCLE
Bosch2012, Auto Mechanic
Category: Car
Satisfied Customers: 3
Experience: Expert in diesel fuel injection machanical and electronic on vehicle fault finding
Bosch2012 and 6 other Car Specialists are ready to help you
Expert:  Auto_Enlightenment replied 2 years ago.

Hello, I'm an ASE Master Technician and I would be glad to answer any questions you may have. Please refrain from rating me until you are satisfied. Feel free to continue our conversation for as long as you need.

My opinion is as follows. The fact that your tachometer is now stable suggests you correctly identified and repaired your problem. Anything that prohibits a proper connection would essentially cause the circuit to go open which would interrupt the circuit causing problems. In your case, while it sounds like you had a connection on the tach feedback, it was a poor connection causing the fluctuation. It would also be good to check the terminal fit/drag. In addition to contamination causing a poor connection so too will a poorly fitting terminal. You would need a pin(sewing needles of various diameters may work) the same size of the pins in the ecu and associated connectors along the circuits path. I have special tools for this which have terminal pins of varying diameters and shapes which you simply insert into the female terminals then pull out. What you are looking for is sufficient drag on the pin to indicate the female terminal is good and tight. If the pin pulls out easily with little or no drag then the female terminal is too loose and would need to be either repaired or replaced. You need to be very careful not to use a pin that is too large as it will spread the female terminal open wider making your problem worse. I'd also make sure that all of your wired terminals are pushed all the way forward in the connectors, sometimes they can back themselves out over time .

I honestly believe you fixed your problem and the proof is in the pudding(it works). I've seen a lot of problems resolve themselves simply by unplugging the connector and plugging it back in. Sometimes a pin has backed out a little over time or there is corrosion which is wiped clean when you unplug and replug.

If there were an issue with a circuit board etc then I suspect it would still be acting up even after cleaning up the connections. If it happens to return then I would start by checking the connectors pin fit. Make sure they're tight and staying put inside the plastic connector(give them a little tug). Then I would check any pins soldered to a circuit board(i.e. ecu). Sometimes a poor sporadic connection comes from one of these pins starting to break free from the circuit board at the solder joint. You can usually only tell by looking at the solder joint while wiggling(gently) the pins.

If you need me to elaborate on anything or if you have any other questions, please don't hesitate to ask. Thanks.

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Excellent reply, and also very quick. Really sounds like the Expert knows what he is talking about. I will be back to use your service when I need more help with my RV. Dutch USA
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
  • http://ww2.justanswer.com/uploads/TE/TedG/2012-6-15_14759_avaLarge.64x64.jpg Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    1596
    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    1311
    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    ASE Master Tech

    Satisfied Customers:

    2367
    ASE Master Tech advanced level specialist
  • http://ww2.justanswer.com/uploads/SU/supermechanic/2013-8-23_03546_500.64x64.jpg Jerry's Avatar

    Jerry

    Master Mechanic

    Satisfied Customers:

    1906
    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    942
    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
  • http://ww2.justanswer.com/uploads/ST/Steve7654/2012-6-5_215929_japic800x660.64x64.jpg Steve's Avatar

    Steve

    Auto Service Technician

    Satisfied Customers:

    1980
    25+ yrs experience as a professional working technician; ASE L1 master technician
 
 
 
Chat Now With An Auto Mechanic
Bosch2012
Bosch2012
3 Satisfied Customers
Expert in diesel fuel injection machanical and electronic on vehicle fault finding