PDA

View Full Version : 95 drivability issue, car cuts out



bt04250
07-05-2016, 08:33 PM
So I have a 95 manual sc. I bought the car last year knowing it needed some work and now I'm down to the last few issues(I think). so the main problem has came and went and changed I guess. it started out the car would cut out like it shut off when I hit big bumps going down the road or If I got wheel hop, at this point the check engine light would also flicker. it progressively got worse and would cut out for pretty much any bump. I then began to notice anytime I would try and back up the car would stumble and die. I checked codes and had multiple mass air codes, i replaced the mass air and the barometer. car runs much better performance wise but the problem still was there, much worse when hot. at this point all my mass air codes where gone but i then had a code 212. I search and came up with my that i thought my ICM was bad so i replaced it with no change what so ever. at this point i began to notice some odd stuff. sitting and running in the driveway anytime i would pull the shifter backwards (so into 2,4 or reverse} the car would stumble and die, again check engine light flickered. i then started the car and if i shook the engine again it would die. i checked and pulled and pushed harnesses trying to duplicate the issue with no luck, out of nowhere the car stopped acting up. i then drove it 2 days no problems, then this morning under moderate accel about 3k rpm the car bucks and cuts out like before, does it both first and second gear but 3rd seems okay. so with all this going on i also have a koeo code 564 for electro fan circuit which i blamed on the relay control module since i heard stuff bouncing around in there, i replaced that today at work. on the way home i turned the AC on and it just blew hot air. so i got home and started to track that down. when i have the module bolted to the bracket and secured to the cross member my ac clutch wont turn on. as soon as i remove the unit from metal contact it sends power to the ac cutch. ive driven the car with the module bracked grounded and undgrounded with no drivabilty changes. at this point i have no stored codes but continue to receive the 564 koeo no matter what i do. any help would be much appretiated. I'm not sure if these issues are related or not but trying to give as much info as i can. thanks in advance and sorry for the novel i just typed lol.

sam jones
07-06-2016, 02:13 AM
Good evening

This applies to 1989 - 1993 Thunderbirds. 1994 - 1995 may be different. Refer to Electrical and Vacuum Troubleshooting Manual.


From your description of problems I would start with the Intergrated Controller Module (ICM) ground first. Trace the negative battery cable to the drive side radiator support to a ring terminal secured with a 8 mm bolt. There will be a two piece 1- cavity connector black connector. Check for corrosion, damage, overheating and or security. Correct any defects.

Next inspect power wires to the ICM. Inspect the alternator harness black 16 gauge fuse link connecting to the yellow 10 gauge wire (underneath the radiator support) and finally to the ICM though the connector at the passenger side of the radiator support with black and orange wire. Check for corrosion, damage, overheating and or security. Check for battery voltage (key on engine off). Correct any defects.


Good Luck.

bt04250
07-06-2016, 06:56 PM
Thanks for the advise. I believe I'm starting to get somewhere, with the key off I have less that .5 ohms at all my grounds, including the plug for the icm. I then switch the key on and checked again, I now have over 100 ohms at the icm plug, if I check ground resistance while car is running I have about 160 ohms, when I turn a/c on it climbs to over 300 ohms. these are all being tested with a cold car, it has not been driven since yesterday. so if I'm thinking correctly I should have good ground(less than 5 ohms) from battery negative to any ground. in all my test I used the negative post as a base point then verified resistance using a chassis ground location. please correct me if I'm wrong about my ground theory.

sam jones
07-06-2016, 11:06 PM
Good evening


Automotive electrical troubleshooting can be tough. I am not a expert so I reference the forum, You Tube, manuals and schematics. One reference book I highly recommend is Vaughn D.Martin Automotive Electrical Systems; Troubleshooting & Repair Basics.

What I believe you are measuring is co-mingling of powered circuits at the negative battery ground not isolating a specific ground circuit. In this case you should be checking for Amps/Voltage not Continuity/Ohms. I assume the voltage was very low during the test because the Continuity scale of the voltmeter is still working. I would perform a voltage ground check at the specific circuit. Get access to a Thunderbird/Cougar Electrical and Vacuum Troubleshooting Manual for your specific year.


Good Luck.

SCarSC
07-07-2016, 10:45 AM
Is the ignition switch an issue on 94-95 like it is with 89-93?

potshotscott
07-07-2016, 01:07 PM
Ground is ground is ground - meaning that from the negative battery terminal to any and all ground points in the car you should measure a very low resistance value. I'll have a look at my '94 to see if what you report happens to me as well. However, the ground plane should be constant regardless of current flow through any and all of the systems. I'm assuming that you're measuring from the ground of the battery to any and all of the grounds under test? If so then yes, the resistance ought to be a constant.

I spent 5 years as an avionics technician on EA-6B Prowler and have never experienced the phenomenon you report although our jets did not have 12V batteries. :D

KMT
07-07-2016, 01:20 PM
Ground is ground is ground

Ford loves to make/break circuits via grounds which can add another layer of complexity to the SC when it comes to troubleshooting, but you're right...low resistance is the key. One way to help troubleshoot is to add temporary grounds, but always be sure cables and mount points are clean and if in doubt, remembering how old these cars are makes it a good investment to replace where practical. SCs live and die by their grounds/ground paths. And as noted, an EVTM can help point them all out.

bt04250
07-08-2016, 07:54 AM
so i decided to replace the cam sensor even though i didnt think it was the problem. well as i suspected no change. as for the grounds, I am using the battery as an itinial test point then verifying with other grounds with no change in resistance when checking other spots. i kinda think i may have a bad pcm or ground somewhere. I needed a break from the car since im just getting annoyed at this point. i will get back at it this weekend. I do have the ford service manual and a evdm for the 95 and trust me ive been using them a lot to fix a number of goofy issues. also would love to know about other 94-95's doing the same resisitance jump when key is turned. will keep updating as i find more info.

KMT
07-08-2016, 09:41 AM
This no-start link is for an '89, but you seem savvy enough to maybe glean bits/pieces (ground resistance) that might help your cause:
http://mnharms.com/tutorials/disnostart/

And yes, feel your pain - not an easy task at times.

bt04250
07-08-2016, 11:38 AM
Thanks I'll definitely see what I can use from it. As for the savy part, I'm a diesel truck and equipment mechanic. I know 6.0 powerstrokes like the back of my hand just don't work with gas enough lol.

bt04250
08-06-2016, 11:40 AM
Well thanks for all the help. I'm pretty sure those issues are fixed. Found a few goofy things going on, finial issued was the pcm. Now on to the next lil issues lol.