My Bronco always cranks up fine. I will be driving for a while and then my truck dies. I can feel the steering lock up and power is gone. HOWEVER if I push the pedal all the way down right when it starts to die then it will sometimes kick back on. It never shakes, it cuts out all at once. I sometimes can start it up immediatley but if not, i let it sit for 10- 15 minutes and it works again. I changed my fuel filter, fuel relay, and fuel pump. Hasnt changed anything. I got perfect fuel pressure. Any ideas?

 

First off, welcome to FTE an the Big Bronco Forum. We will endeavor to get you the most accurate information we can muster.

You can run KOEO and KOER tests and pull the fault codes to help pinpoint where the issue might be. If you need information as to how to perform these tests check HERE. With the fact that the truck has died on more than one occasion from what you have said, there should be at least one or two codes that should point you in the right direction to fix the problem. Once you get the codes, let us know what they are. We can elaborate on the specific causes for the codes to have appeared.

 

It's probably either the PIP or the TFI.The way it only does it while warm makes me think TFI.If it turns out to be the PIP,it's easier to swap out the complete distributor,but most remans come with cast iron gears,so they may need swapping.
I went through this recently,but like greystreak says,pull codes and take it from there.

 

Also, after you pull the KOEO codes check the CM, Continuous Memory, codes. You can use a paper clip but I like my $35 code reader and keep it on board. If it dies, I pull CM codes in just a few minutes to rule out ignition problems and if the code is good I pour in some more Heet. Before you replace anything check to be sure the grounds are perfect. My problem was the ground on the fender next to the battery. The stud was turning in the fender and the wires were loose. Two small wires and a battery ground connect there. There are four stations here that have gas with no ethanol and everything runs better on it.

 

I am going to dedicate my afternoon tomorrow to checking those codes and I will get back to you guys. I have to ask a few things though. What is HEEP? What is a TFI and what is a PIP? Sorry for the newbee q's but I bought this truck as a project to learn these sort of things. Also, I dont see how it would be a grounding problem that "fixes" itself after I let it sit for a while.

 

"HEEP" is a Bronco owner's reference to any of the pesky little ants that run around getting stuck asking us to extract them. The rest of the world just says "Jeep".

Oh, you meant Heet... its fuel system dryer. Little yellow bottle with blue letters "HEET" you can add to a tank of gas especially of you are getting a lot of missing or poor throttle response. This product is helpful in winter when moisture condenses in the fuel tank causing these issues.

TFI (Thick Film Integrated circuit module) I could explain the reason for the "thick film" reference but its hardly necessary. (If someone really wants to know, ask.) Otherwise referred to as the ignition module or ICM (Ignition Control Module). Its a grey (and sometimes black) electronic device mounted to the distributor on models up through 1990-91 and then on the driver's side inner fender in a big heat sink from 91 up. It has a seven pin connector at one end and controls the spark timing.

PIP (Profile Ignition Pickup) is a "hall effect" inductive trigger (I know, I know... a lot of electronic BS but that's what it is). It is basically a magnetic sensor down inside the distributor that triggers an electronic impulse as a ring with a series of metal teeth passes between the magnet and the other half of the sensor. The ring is attached directly to the distributor shaft and allows the TFI/ICM and the PCM/ECM (Powertrain Control Module/Engine Control Module) to "read" the impulses it sends out and adjust spark timing accordingly.

 

"Also, I dont see how it would be a grounding problem that "fixes" itself after I let it sit for a while."

I did not understand it it either. So I replaced the ICM three times, distributor three times, coil once before I found the loose ground and solved the problem.

Oh, also opened the wiring harness and traced a wire to hunt a resistor that is not there on the CCD computer controlled dwell system.

 

Well I have to admit that it was a little confusing but I think i got it figured out. CM was 11-11 so System pass?

Then KOEO was 14, 67, 95, 96.

So now what? From what I read, fuel pump-ish? I already changed it. Hmmm.

 

Last two are fuel pump related, if you have replaced the relay and fuel pump itself, then check your grounds. Good grounds that are not corroded are what you need as the computer runs a low voltage check system of only 5 volts vs the rest of the system at 12 volts. 5 volts will be far more affected by high resistance cause by corrosion than 12 volts but corrosion is always the enemy of any electrical circuit. Good circuits equals one less thing to trouble shoot on a computerized system.

You also had an erratic PIPS signal. This is related to your ignition and is part of the distributor IIRC. It is not the TFI but both work together to enable the ignition to function correctly. If one or both fail it can be erratic until complete failure occurs and then you have to get the correct part. The ICM/TFI has two versions that are color coded by my understanding as I have never replaced this piece, but as a rule replace with same color only.

The 67 code is more a warning code than anything. It checks to make sure the neutral safety switch is present or at least can be seen by the computer, but not if the neutral safety circuit is in good condition. If you can start the truck from the key switch in the cab, then you probably have another corrosion problem in the circuitry, else if you have to jump start the truck under the hood then you need to make sure the circuit is good between the ignition switch and starter selinoid. If this has failed I would start at the Neutral safety switch/MPLS on the autos, or the clutch interlock switch on manuals.

 

How many grounds should I check and where? Just any I can locate under the hood hooked to each major component? Also, if they are all good and clean not shorted or corroded then what is a suitable replacement distributor fo rmy truck and any recommendations on where to buy? Napa doenst have one.

 

Yours may be different from mine. If there is a negative battery cable pigtail over to the fender start there. Be sure the stud is not turning in the fender and loose. Next, near driver's side hood hinge by the code pulling connector.

I'm not aware of the fuel pump ground location.

 

I did check the pigtail coming off the battery and it looks good as does the one on the driver side. I didnt have a multimeter to test the OHMs but I will clean them with some Soda water. Heard that works. They are however not loose. I traced the wireharness off the fuel pump as far as I could without taking stuff off, cant locate ground. Assuming thats all good, the Distributor...What is a suitable replacement?

 

The answer is the very first code... Code 14 is PIP sensor/circuit failure. Stop chasing grounding issues right now because the computer has already told you that's NOT the problem.

You can replace the PIP sensor however, I would recommend checking the distributor wiring harness for worn wiring insulation first. Since the PIP sensor can be affected by strong RF (radio frequencies) make sure you don't have any exposed conductors in any of the distributor wiring. Move on the the connection between the dist. and the main harness. Follow by checking the connection at the TFI/ICM. If all checks out, remove the cap and rotor from the dist. there are two small bolts holding the PIP excitor ring to the dist shaft. Remove and carefully remove the excitor ring... don't bend the teeth on it! Once it is out, you can get at the PIP sensor to replace it if necessary.

 

No more grounding searches. Done.
Ok, next thing during lunch tomorrow I will be checking the Distributor harness and TFI / ICM Cables.
I have read a bunch of forums that say its easier to change the whole distributor, but I am willing to put in the time here to learn and do it right. With that being said, I came across many forums that discuss something about not swithcing a grey and black something or other. What should I look for and which part is it specificlly that I need to check to avoid replacing the wrong part?

 

The black and grey part is the TFI module on the outside of the distributor. To replace it requires a Special thin-walled socket or you can just make the access hole bigger to get out the bolts.

The distributor can be replaced as a single unit, but if you dont know when the last time was that it was even removed from the block you could potentially have a distributor that is stuck in the block. It is easier to replace the PIPS unless you do have a worn distributor or you have damaged the distributor trying to remove it from the block.