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 Chad Your Own Question

Chad
Chad, Lead Master Tech
Category: Jeep
Satisfied Customers: 1041
Experience:  Electrical master,Diesel Specialist,Lead Tech/shop foreman
Type Your Jeep Question Here...
Chad is online now
A new question is answered every 9 seconds

1998 jeep grand cherokee limited: crank sensor..the fuel pressure psi

Customer Question

i have a 1998 jeep grand cherokee limted with a 5.2l that has no codes i replaced the coil the cam sensor and the crank sensor and checked the fuel pressure psi ok the coil wire has power at key on but shuts off and wont go hot while its cranking i have been checking it aginst my friends identical jeep and still cant find the problem
Submitted: 3 years ago.
Category: Jeep
Expert:  Chad replied 3 years ago.
Have you checked the ASD relay and all fuses?
Customer: replied 3 years ago.
yes sir
Expert:  Chad replied 3 years ago.
How did you check the fuses?
Customer: replied 3 years ago.
by eye and with a test light after no sucess
Expert:  Chad replied 3 years ago.
OK, I'm going to have to go over the wire diagrams for a few minutes. But I might come back and ask you questions during. And knowing that you have a test light, I will need you to do some testing.
Customer: replied 3 years ago.
ok im not shure how late i will be abel to work this is my first time here can we pick up in the morning
Expert:  Chad replied 3 years ago.
Yea, thats fine. I will leave you some stuff to check for me. I will be at work tomorrow, but will check the site from time to time.
Customer: replied 3 years ago.
thank you
Expert:  Chad replied 3 years ago.
ASD Diagrams
graphicgraphicgraphicgraphicgraphic
Expert:  Chad replied 3 years ago.
I also need you to check with the test light, remove the ASD relay, while cranking, which pins have power?
Customer: replied 3 years ago.
i have the info you need but i dont k now what the pin numbers are one prong has power constant and one pin constant while cranking
Expert:  Chad replied 3 years ago.
OK, that is what is suppose to happen.The one that has power while cranking, is also suppose to have power when it is running.Do you know how to remove the cover on the relay? When you remove the cover on the relay, with it installed, while cranking it will actuate and move the lever over.It should stay engaged while running.
Customer: replied 3 years ago.
it wont run at all and not shure if i bought the right new one im looking for the old one i will take apart and check now
Customer: replied 3 years ago.
it disconects at key on for 1-2 seconds then makes contact when it looses power is the pcm keeping it shut down is there a way to bypass it(the relay)to see if it will start my brand new battery is getting low i have a truck charging it d
Expert:  Chad replied 3 years ago.
If you fold a paper business card in half you can hold the contacts closed inside the relay with the cap off of it. Also you can try swapping the ASD relay with the starter relay. You know the starter relay works.
Customer: replied 3 years ago.
ive tried that with the contact seperated first cause thats how it is at key on then with it closed and i tried jumping the power to the coil with the relay removed and with it installed also i can send power to the coil plug from the relay
Expert:  Chad replied 3 years ago.
I would like you to try something for me real quick. Unplug all the O2 sensors and try to start it.
Customer: replied 3 years ago.
nothing
Expert:  Chad replied 3 years ago.
OK, I am missing something.I have seen this before.And I am having CRS right now.I am going to go back over the diagrams and everything you have said and think about it for a few minutes. I'll get back to you as soon as my CRS goes away.
Customer: replied 3 years ago.
:) i hate when i get that lol thanks for the little laugh
Expert:  Chad replied 3 years ago.
No problem. Right now I am leaning towards the PCM is bad. But I don't want to say that yet. Bad thing is I had one just like yours in the shop a few months ago doing the same thing. Just can't remember what the repair was.
Customer: replied 3 years ago.
ya is the pcm on the firewall by the coolant tank is it the same thing as the ecm or is there a ecm and pcm would the pcm allow power to go to the coil at initial key on if it was bad
Expert:  Chad replied 3 years ago.
Yea, the PCM is the ecm. It is on the firewall by the coolant tank.Yea, if it's not seeing the ASD output on the initial key on, it will stop power to the coil fuel pump and everything else.
Customer: replied 3 years ago.
oh ya my fuel pump works about 45 psi was the first thing i tested would it kill spark and not the fuel pump if its the asd
Expert:  Chad replied 3 years ago.
No ASD should kill both.But let me double check that.
Customer: replied 3 years ago.
ok
Expert:  Chad replied 3 years ago.
But I just found this.
The ASD supplies battery voltage to the fuel injectors, ignition coil and oxygen (O2S) sensor heating elements. The ground circuit for the coil in the ASD relay is controlled by the powertrain control module (PCM) The PCM operates the relay by switching the ground circuit on and off.
So, the PCM is most probably the cause.
Customer: replied 3 years ago.
ok ill get one orderd
Expert:  Chad replied 3 years ago.
alright.
Customer: replied 3 years ago.
hey one more thing alot of people on the internet have tried all of this all of the sensors and the pcm and still had troubles what do i do if it doesent work
Expert:  Chad replied 3 years ago.
Then you will have to start opening up wire harness and looking for wire damage.

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:

 
 
 
  • Thank you so much for your answer. My initial estimate was $325; I got it done for $100 - part and labor. Lynn B. Ormond Beach, FL
< Last | Next >
  • Thank you so much for your answer. My initial estimate was $325; I got it done for $100 - part and labor. Lynn B. Ormond Beach, FL
  • I was skeptical at first but thought I'd give it a try. I was pleasantly surprised. Your site actually is a quality service that I would recommend to others in a heartbeat. Stan Sayre, PA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
 
 
 

Meet The Experts:

 
 
 
  • Mark's Avatar

    Mark

    22 Year Factory trained technician

    Satisfied Customers:

    2548
    Jeep factory training........25 years in the industry.
< Last | Next >
  • http://ww2.justanswer.com/uploads/MO/MoparCertified/2012-6-7_4142_mechanic.64x64.jpg Mark's Avatar

    Mark

    22 Year Factory trained technician

    Satisfied Customers:

    2548
    Jeep factory training........25 years in the industry.
  • http://ww2.justanswer.com/uploads/jeep10000/2008-9-18_222938_192601.jpg Chris's Avatar

    Chris

    Shop Foreman

    Satisfied Customers:

    2265
    Jeep and ASE Certified Master Tech
  • http://ww2.justanswer.com/uploads/ke4ich/2009-08-12_212931_DSC02211.JPG moparfl's Avatar

    moparfl

    ASE Certified Technician

    Satisfied Customers:

    1128
    ASE Master Tech Chrysler Dodge Jeep Master Tech
  • http://ww2.justanswer.com/uploads/nvltgo/2010-10-18_211525_youranswers.jpg Dave's Avatar

    Dave

    Jeep Master Tech

    Satisfied Customers:

    1120
    Chrysler Triple Master, ASE master Tech AA degree in Auto.
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    805
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
  • http://ww2.justanswer.com/uploads/CD/CDJMastertech/2012-6-9_201455_JustAnswerProfilelarger.64x64.JPG CDJMasterTech's Avatar

    CDJMasterTech

    Jeep MasterTech

    Satisfied Customers:

    576
    Factory trained and certified Jeep Master Technician, ASE Master Technician
  • http://ww2.justanswer.com/uploads/jeepmopar76/2009-3-18_2204_63998760.jpg jeepmopar76's Avatar

    jeepmopar76

    Jeep/Chrysler Triple Master Tech

    Satisfied Customers:

    572
    32yr ASE Master Tech, 9yr Chrysler Master Tech, 19 yr Jeep Dealership service including AMC/Eagle