2012 Grand Caravan 3.6L intermittent no start current ramp lesson
Just wanted to share something i think some of you are likely familiar with here. Vehicle was towed in for no start and as life would have it it starts up for us upon arrival. Scan for codes no codes stored. Being familiar with the fuel pump relay failures in these ( integrated into TIPM Module ) and the bypass relay kit from Chrysler i decided to current ramp the fuel pump first. The current waveform of the fuel pump looked great. Next i decided to go into the PCM and i was going to turn the fuel pump on and off through active test and see if i could catch the relay acting up. What i found next was realy cool. On this particular vehicle it has a toggle test which proved to work out great. I changed the time base on my scope current test and toggled away. Minutes later i captured the relay not working at times. slam dunk baby ! not only did i capture the relay intermittently not working i could see that the TPIM module was still commanding the relay coil on and off when it acted up. The contacts were not closing properly or burnt. This tells me that the issue truly is the relay and not the TIPM module itself. Hope this helps others who come across these platforms when the vehicl shows up running and you are hoping it acts up in your search for truth. Chrysler does have a TSB for this kit and how to install it.
I suggest that you monitor voltage also when testing such circuits. First, you can determine if the relay contacts are substantially degraded. Second, it eliminates the possibility of getting fooled by an intermittent open down-line of the test point.
I know that GMs have similar issues as the pumps get older and draw more amps and takes out the relay.This is a first time that I heard it from a Chrysler product.Thanks for sharing
Great job explaining the process. And the captures are a real help.
At first look I agree - looks a bit high so I look up the spec from our catalog. The Delphi pump spec is 11 amps (average) so the high and low swing of the current ramping average right around that number on Robert's scope. The flex fuel pumps have a slightly different design that draws more current than the pumps rated up to E15.
Hi David. Is this catalog with the fuel pump specs available to anyone? Thanks, Mike.
Yes, just google Delphi Auto Parts, click on catalog, then find your application, click on the p/n and then click on parf info.
It's in their online catalog. Never realized that they had amperage specs. included. partcat.com/delphi?_ga=2.5…
Looks to be around 10 amps or so. Thats fairly normal. The uniformity of the current trace is what is important, since there is no real spec available to us for what the current should be. (If you are referring to the 16 amp spike,that is in-rush current from him toggling the relay off and on)
On which capture? They are far different. I suspect that he didn't have his ammeter zeroed for the first one.
I screen shot these waveforms off my Pico I should leave the settings when I post stuff like this takes away confusion. The probe was zeroed in both captures. And to be clear the real reason I posted it was to share how one could toggle the relay and watch the relay ( which is not accessible ) when the vehicle is not acting up regularly. I could have started it half the day before getting it to…
I don't understand what you are trying to communicate regarding the displayed current in your captures. The one shows approximately 11A, the other shows approximately 9A. Yes, your second capture indicates that there was an effect in the motor circuit when the relay was commanded. I would need to know the location of the ammeter and zoom in on the capture before calling that certain evidence…
The M25 fuse was removed with a fused jumper wire installed in its place. This is where both the current waveforms were taken.
Tip- in situations such as this, scope the voltage on the circuit first, before removing the fuse. You can easily identify whether or not the relay contacts have a problem, you will not modify a connection issue in the fuse box by the wiggling which occurs when removing the fuse, and you can wiggle the fuse while watching for voltage changes. THEN remove the fuse for current testing, if needed…
As a side note I just became a member here and I am so glad to see some old names from the early iATN days resurface. I wandered away for many years because people were just getting way to negative and abusive to one another there. Thanks for having me and sure am looking forward to reconnecting with some folks and getting to know some new ones as well. I see a treasure chest of knowledge here…
Me too Robert. I gave up on Iatn quite a while ago.
Did not know they had a relay bypass kit for those. Good to know. thanks.
Done the relay kit before, but I haven't seen the "toggle test" in the scan tool yet. Great tip!
Here is one I took from my in-laws Caravan this weekend coincidentally. Very intermittent in their case, it took me 15 minutes to catch the drop out at the end. Instead of using the toggle function in my scan tool the activation you see is me cycling the key on to prime the pump. Also, the main concern that the van would intermittly not start. I would have liked to capture the complete failure…
Very common issue with TPIM modules on Chryslers and Jeeps that have the fuel pump relay integrated in it. This type of testing is good when the symptom is intermittent. Another symptom is the fuel pump real stays on ( latched ) and kills the overnight (intermittent) same issue different symptom.
Here is the PDF to install the fuel pump bypass relay if someone needs it in the future.
Bob, this is a great case study and an eye opener for me. Since the vehicle application didn't call out a TSB (but the Mopar document you provided definitely fixed the van) a lot of techs (and trainers like myself who struggle to stay up to date) would have no clue had they not seen this. An eventual (and expensive) TIPM replacement would be the solution unless (maybe) you "YouTubed it"…
This is an interesting issue. I am very surprised by how many responses state that this issue and repair were not known. I expected that almost everyone already knew about it. Part of the problem is that FCA only presents this repair and corresponding TSB for certain models, though more are affected the same way. I don't know why they did that, but anyone who works on FCA/Dodge/Chrysler/RAM/Jeep…
To be clear the two symptoms we have encountered through the years is intermittent no start ( sometimes described as long crank ) and intermittent dead battery ( that is very common ) some customers will comment they heard something still running when they shut the vehicle off.
Yes very common problem on the Rams, grand caravan, and Jeep as you mentioned. I went for the harder fix, by replacing internal relays. I didn't know they actually had a kit for this issues. There are few internal relays on those TPIM, one fuel pump which is the most common one, and also there are for the front wiper and another for the rear wipers. Thanks for the case study!!!
Where have you found the replacement relays at? This would be the ideal repair instead of splicing wires.
chrsyler carries the relay kits the parts you will need are in the PDF I posted above. The relay kit does not come with the inline fuse holder and fuse you will need either. All 3 parts are listed in the PDF.
Sorry Robert, I was asking about the replacement relay internal to the TIPM that Saul had mentioned.
Nice Job. So you installing a bypass kit?
Yes bypass kit was installed and issue rectified