2.3L ('83-'97) '95, 2.3, manual. P0232. Check the easiest thing first.

[MADMODDER]

Good afternoon. This is a story to be heard and a warning heeded.


For those not in the know, I'm a euro tech. I recently got an apprentice, who recently bought a '95 Ranger. The other day it quit on him. I thought I'd let him use this opportunity to learn some hard lessons. I, somewhat, showed him how to navigate alldata. Explained how the system works and made sure he didn't do anymore damage. We scanned the truck and came up with P0232. We found the fuel pump fuse was blown. Somebody had put a 30amp fuse there and its suppose to be 20. So we put a 20 and it popped. Replaced it again and did a quick google. multiple sources said the fuel pump is the most likely culprit. He asked if we should replace it and I told him, "it is the mostly culprit so you can either shotgun a fuel pump or confirm with diag."
He chose to shot gun because he needs transport. As we all do.

So we ordered a fuel pump and upon removing the bed, we found the fuel pump harness was smashed between the tank and the frame. Seeing that, we thought "surely there is a short there." but we already have a new fuel pump so what the hell. Replaced the pump, ohm'd out the harness and it met spec. So we thought, "maybe the short was in the pump" and with that replaced, we tried to start again.

The fuse blew again.

So we printed off the electrical diagram and went to town. I figured I use this chance to exercise my electrical skill because I don't get to often and teach my apprentice a few things. Mainly I=E/R but also what each of those things are and their relation to each other.

With key off, we confirmed the fuse has 12v as well as lead 3 at the pump relay.
lead 1 has .9ohms.
lead 2 has 2.1ohms
lead 5 has 3.8ohms

with key on, we confirmed lead 3 still has 12v.
lead 1 has 12v
lead 2 has 12v
lead 5 had 12v for a 1-2 seconds then 13ohms.

Seemed odd, it should had 6-8V.

We tested the relay, it is good.

So we checked grounds, those are not great, not terrible. It is 31 years old. Thing 1, 2 and 3 have been in there. But 1 thing at a time.
Checked the inertia fuel shut-off (IFS) its good.
Checked the wire from the lead 5 to the IFS, its good.
Check the wire from the IFS to the fuel pump, its good.
Checked continuity between the fuel pump relay and the PCM. They are good.

So what are we missing?


The PCM itself. There is no clear test for it you would need to map out the pins and figure it out the long way around.
Or you could remove the PCM and open it, which is what I did.
Upon opening, we found a section is fried.

Next time, he will spend 5mins to remove the PCM and make sure it isn't fried before replacing the fuel pump.


As stated, I'm a euro tech and not very familiar with Fords. So if I am missing somethings, please let me know. Likewise, if you have info to add that could help somebody in the future, it would be much appreciated.

 

[SenorNoob]

Maybe I'm blind, but what in the PCM is "fried"?

 

[BobSacamano]

Maybe I'm blind, but what in the PCM is "fried"?

Was thinking the same thing.

 

[MADMODDER]

Maybe I'm blind, but what in the PCM is "fried"?

Was thinking the same thing.

All that black and white stuff, center left.
is it not burnt?

 

[SenorNoob]

That looks like factory anti corrosive to me. There shouldn't even be anything plugged into that to cause it to burn. I'd bet a little contact cleaner and a paper towel and looks like new.

 

[MADMODDER]

There is nothing plugged into that spot. but it doesn't need to be plugged in there for that to burn. little bit of corrosion there causes the lines to connects and short.

If that isn't burn and the PCM isn't the problem.

what is?

 

[SenorNoob]

I don't understand the fuse blowing. PCM couldn't even cause that in this case. It only grounds the coil of the relay to run the pump. I do notice that fuse is labeled "Fuel System/Anti Theft" No idea how that plays into the system. My 92 doesn't have that. I get the impression there is a junction on that fuse that isn't in the diagram above...

The fact that you had power for 2 seconds on pin 5 says that at least that part of the PCM is working as intended. It doesn't ground the fuel pump relay coil again until engine fires and gets to something like 500RPM. You can safely apply ground on that pin yourself to test further.

Also IDK where 6-8v came from. It would be 12 at that point. Assuming of course the other lead of your meter was on a good ground.

 

[MADMODDER]

If the PCM grounds out internally, it could be a short to ground, decreasing resistance, increasing amps, blowing the fuse.
Which is what im suspecting is shappening.
Im also not sure why its labeled with the "anti theft" title.
The only thing anti theft about this car is the key and its a manual.

Safely apply ground to lead 5?

The 6-8V is a reference voltage after the 2 seconds and before starting the car.

Lead 5 is not charged during reference voltage.

 

[BobSacamano]

The antitheft/RAP module shares that fuse with the fuel system, if so equipped.

 

[BobSacamano]

Here are a couple of links where RonD is trying to help someone with the P0232 code. Maybe it will help you figure it out.

Thread 'Fuel pump voltage issue (7V), occasional P0232 Code'

Mar 20, 2015

I have a 98 Mazda B4000 with a 99 4.0L SOHC Explorer engine that was swapped by one of the two previous owners. I have become pretty proficient at doing some sensor rewiring and reading/intrepreting both vehicle wiring diagrams, but the fuel pump has me stumped. The fuel pump runs continuously with the KOEO, and if left that way for more than 5-6 seconds without starting the vehicle it will throw a pending P0232. It also runs without the relay and with the inertia switch unplugged. Before anyone suggests anything I finally figured out why, and after already having swapped my ECU, lock...

• Caesar
• Replies: 4
• Forum: Electrical Systems, Wiring & Gauges

Thread 'P0232 fuel pump secondary circuit high'

Mar 11, 2018

My issue: 2004 Ranger 3.0L started to randomly shut down. Would start after about five minutes then progressed to not starting at all. Engine turns over, registers rpm, no flashing theft device, inertia switch not tripped, no fuel pressure at rail.

I purchased a code reader and it is throwing the P0232 fuel pump secondary circuit high. I have since replaced the fuel pump relay, the fuel pump itself, and the rpm sensor. After reading the forum’s I have verified that the PCM relay and fuel pump relay are good relays themselves however, when cycling the key the relays do not energize and...

• Gunfighter34
• Replies: 1
• Forum: 3.0L Engines

 

[MADMODDER]

I read through both of those.
Both threads lead me to believe the PCM is the culprit.