Transit 2.5TD 1996 - EPIC problems

[The-Duke]

Hello Transit Experts & Friends.

I think I have a very special, "EPIC" problem with a Transit 1996 2.5TD camper van, fitted with a Lucas EPIC (8720A011A).

History: The Transit of the In-Laws quit running or ran very flaky with black smoke and intermittent cut-offs. They took it to a "mechanic" (friend) that "diagnosed" a flaky connection of the plug to the EPIC.
Solution: The guy cut off both sides (car-plug & socket in the EPIC) and soldered all 19 wires together.
Current Situation: Transit starts & runs quite well in idle, but stays in limp mode (red engine-light) without power.

Now, after finally finding another shop that has a Laser 2000 (hard to find) to actually read the ECU faults, we got hold of these fault codes:
1170 - ESOS Valve - OK, sometimes the engine doesn't stop immediately with the key. As far as I understand, this code CAN cause limp-mode, but can be temporarily "solved" by stalling the engine while turning the key to shut it off. This happened reportedly already before the "big"  current problem, so I'd rule this out for the moment as the main source of the limp mode.

1190 - Calibration Resistor: Ah well, the soldering guy left off two wires in the car-plug that he apparently couldn't find a corresponding wire in the EPIC's socket, not knowing that the resistor is part of the socket. Even worse, the whole socket-case of the EPIC is gone now, probably trashed, so I don't have access to the original resistor/the resistor's value.
I temporarily tried to solve this by fitting a 6.8k resistor on the two "free" wires. This value should match a setting (#1) from the service-manual. According to the manual, this fault results in a "slight loss of power", so I'm tempted to say that this can't be the limp-mode reason either. 

1171 - Rotor position sensor: As far as I understand, this is an electrical check of the sensor and a failure WILL cause limp mode. Investigation of the resistor values seem to indicate that the guy that soldered the wires swapped some of them. This is what I currently get (Pin numbers taken from the color-coded car-wires as I don't have the plug for reference):

13 (WG) - 14 (WB): 286
13      - 17 (NR): 45
14     - 17:      330

According to the manual (Chapter 4.1), I think it should be like this:

13 - 14: Temp-Comp. (225 +/-25 Ohms)
13 - 17: Sum of 13-17 + 14-17 
14 - 17: Rotor-Position (48-60 Ohms)

Looks like 13/14 are/need to be swapped? Most confusingly, the wiring is printed differently in Chapter 5.1. Which one is correct? I'd go with the one from Chapter 4.1. Can someone confirm this?

However, after swapping, all the faults are still present, even though I'd assume that at least the one for the calibration resistor should have gone. There is a slight chance that the connections are still bad because so far I couldn't solder all the wires (the gas-powered soldering iron quit working and the car is now located at the mechanic's place with Laser 2000 at a remote location with limited access).

Things I don't know at the moment:
What is the shielding of the sensor's cable usually connected to?
Is this relevant for the diagnosis of the ECU?
Are there any other connections in the EPIC's plug that may have gone now?

The service manual (§5.2) indicates that there are two wires with the same color codes: Wires with NR (brown-red) are connected to 9 & 17 - interestingly they are both parts of the Rotor Sensor (17) and the Calibration Resistor (9) that are now flagged by the ECU. I think I'd have to try to swap those as well, as I don't know what the previous guy might have broken here...

To verify that, I could be to try to measure the connections to the ECU. Which leads to the next problem: Where is the ECU located and how to access it? It seems to be somewhere behind the glove box (right side of the car, German layout). But I can't seem to find a reasonable way to access it... it seems to be necessary to dismantle the whole plastic front cover... really? Any "easy" way to access the ECU?

Swapping the EPIC for a Bosch pump isn't an option so far. Too expensive and too unclear with German regulations.

So far, thanks in advance for any hints or suggestions.

Greeting from Germany
Sascha

[MinorMatt]

1170 - IF the van doesn't switch off on the key it WILL be in limp mode. This is not an intermittant

1190 - if the calibration resistor is missing, this causes quite a severe limp mode! The resistor you have soldered in should "fix" it - assuming its on the right wires.

1171 - Rotor position - this is the sensor at the back of the pump between the 4 high pressure pipes, if this is faulty it will cause a very severe power loss. It looks like 13 and 14 may need to be swapped based on your description. Looks like 13 should be connected to a WG wire (12 on ECU), 14 (9 on ECU) to WB and 17 to NR (6 on ECU).

[The-Duke]

Hi Matt, thanks a lot. You don't happen to know how the rotor position sensor (its green, black and red wires) usually is connected to the EPIC socket, i.e. its pin numbers?

About the ESOS, that's what I told the in-law as well, but he insisted on having had the problem earlier, but without ending up in limp mode. Although I don't 100% trust that... However, I think that this part should be "fixable" by stalling & shutting off the engine... So if all other faults were fixed, with this the only one remaining, the van should run fine until the next shut-off. Correct? I'd like to have the pump working before taking on the ESOS... I've already seen your how-to on that topic, looks easy enough, but will to do that in-place with all those soldered wires .

Oh, good to know that the calibration resistor can/will cause limp mode. Will investigate this further. Seems to confirm that there's more incorrect wiring left...

To identify the wires from the ECU side: any hint how to easily get to it?

[marcrbarker]

Couple of thoughts to take into account based on my personal experience.

About suspected transposed wires & conflicting official information. Probably just swapping things around and trying gets the fastest result . But the most safest fiable reference of how the wires supposed to join up is get from another vehicle the same IMO. Otherwise failing that, greasy worn workshop pages with handwritten red colour alterations tend to be more accurate than the virgin service manual. Why I mention this is a documentation error like a transposed wire may only ever get discovered after a multi-pole plug gets cut-off, quite a rare event. So what I'm saying is don't take everything published as gospel.

The round connector thrown away is extremely cheaply made version of a standard military and aerospace connector. Having the wires directly soldered together might be a bit drastic.

When the problem is resolved, take a good photo of all the colours joining and keep it safe. You may go through all this again if the pump is ever disconnected. Something you can add later on is a generic electrical multi-way connecting block (chock block, recleta) with screw terminals (or one cut into two if too wide). And take a good photo. You can also get a version of it which is two mating halves that plug into each other, so there's no need to unscrew anything when removing.

Shielding is typically grounded at one end only, ECU end, the sensor end blanked off. They usually only screen a twisted pair. Grounding screen both ends provokes risk of noise pickup from circulating currents, unlikely but possible.

Brown/red is ground. According to the schematic, one end of the cal. resistor is grounded and it shares the same ground connection as the so-called "speed sensor" underneath the pump. One of the 2 'free wire'. Violets/ are power supplies that feed actuators. I would expect a fuse to blow if get those mixed up with a ground.

Rotor position sensor. That's the 'axial position sensor'. The ECU uses the signal to know where the mechanism is. Position relates to the amount of fuel delivered, pretty important for the ECU to know what's going on.

[marcrbarker]

rotor position sensor (its green, black and red wires) usually is connected to the EPIC socket, i.e. its pin numbers?

Source: LDV EPIC service manual
Axial position sensor 0-5 V analogue voltage
PUMP/ brown-red / pin 17 / brown-red / ECU pin 6 [GROUND]
PUMP/ white-black / pin 14 / white-black / ECU pin 9
PUMP/ white-green / pin 13 / white-green / ECU pin 12

Source: LDV EPIC service manual / confirmed
Speed sensor (AKA 'needle lift' sensor - ignition timing). This is a 4 pulse per pump revolution.
PUMP/ violet-yellow / pin 1 / violet-yellow / ECU pin 47 [SUPPLY]
PUMP/ white-blue / pin 5 / white-blue / ECU pin 7 [SIGNAL]
PUMP/ brown-red / pin 4 / brown-red / ECU pin 50 [GROUND]

ESOS. If you remember to stall the engine after turning off, the next start up will turn off the engine light and no limp mode. If you remove key and let the ECU shut the engine off after 10 seconds, it will register the fault. You only need to stall the engine once to 'clear' the ESOS fault code. The repeated shaking of stalling fpr each stop may had been what caused the new fault.

[The-Duke]

Ok, thanks for information. Kinda helpful so far.

I assume that "brown/red (NR) = ground" then applies to any NR wire? Meaning that if any of those were swapped, it shouldn't actually matter? That would make some things easier to rule out. I'm familiar with electrics, but not in car-electrics, let alone any special stuff.

I know about the outer wiring, I have a manual titled "Service Workbook - EPIC D.I. Engine Management System". What I'd need is the internal wiring of the EPIC, i.e. which of the axial sensor's wires (red, green, black) usually end up in pins 13, 14 & 17. See this image:

20210922_172945.jpg

My thoughts are, that if something else was broken, there should be more faults logged. Also, being able to measure the correct resistance values at the sensor tells me that it probably isn't broken internally.

I'm pretty sure I'm close, but something's still not right. Looks like I need to check the connections again.

Cheers
Sascha

[marcrbarker]

Image1.gif

Is this it?

Generally speaking with cars and wire colours in a harness, if three or more same colour coming out of a harness they are simply connected together inside. A lot of the time the ECU is looking at voltages between wires. When the same colour wire goes into a ECU, quite often they're just connected together inside the ECU.

[The-Duke]

Yes, that's the sensor in question. It would be great to know which pin numbers (or even better, verified color codes on an existing pump) the red, green and black wires that come out of the sensor correspond with. Yes, I could just try it, but as I don't have immediate access to the Laser 2000 myself (need to let the shop read it and pay for every reading), I'd like to be absolutely sure.

I'd guess that black = GND / NR = #17. Guessing again I'd say that red is the positive voltage (+5V) and green would be the temp-compensated signal/voltage to read. Which would make #13 red and #14 green. Would you agree? However I'm not sure if I can trust the pin assignments of the color codes, as the wiring diagram differs from the one you posted:

rotor-position-sensor.png

?

Here it seems #17 and #14 are swapped compared to the diagram from chapter 4.1, so the color-assignments of the wires (and my assumptions about the readings) may be incorrect as well.

Will have to verify this again, directly at the sensor and go on from there. There's a lot really messed up here...

BTW: Do the faults have to be explicitly cleared with the Laser or will the van get out of limp mode by itself once all errors have been resolved?

Thanks so far.

Cheers,
Sascha

[MinorMatt]

All of the sensors on the EPIC have the same set ofcolours in the wires... connecting them all together won't do you any favours.

If the issues are resolved then the van will run normally again without any further diagnostic input. The management lamp will stay on for 5 seconds on start up to show there are "historic" codes registered - but that is all.

Whereabouts are you?

People have had luck using Forscan and a modifid (can buy them as modified off the shelf) ELM327 for reading fault codes on EPICs

[marcrbarker]

It wouldn't surprise me to find errors in published official documentation. Often in manufacturing they make copies of a golden example for production, then someone documents the golden example after the factory closes for the weekend where mistakes can creep in.
I think the best thing for you is use another vehicle as reference. Someone kindly offering their services would need to unplug their EPIC pump round connector and characterize each connector pin in question, the resistance each one has to chassis ground. Would be a bonus if note the wire color too.

Pump connector pins
13 .......Ohms. Color......... .. (white-green?)
14..........Ohms color....... . (? White - blue)
17.........Ohms color......... (? brown - red)

Harness connector pins
13 .......Ohms. Color.......
14.........Ohms color.........
17.........Ohms color.......

You'd see how yours compares.

There's something peculiar with the brown-red wires. The mechanic may had transposed the brown-reds. Brown is usually chassis ground potential everywhere. This 'axial position' sensor has a brown-red wire (separately goes to pin 6 on ECU) but it doesn't join up with other brown-reds going to ground. It would be peculiar to re-use this brown for 5V, designers get niggled by things like this. So would need to add

Pump connector pins
9 .....Ohms. Color....... .. (? brown-red)

Harness connector pins
9 .......Ohms. Color.... ....
.

I think that would help you a lot.

Fault codes generally clear by themselves and turn off the check engine light, once the condition that caused it has been removed. Stored fault codes that don't maintain the light on are clearable but there's no point clearing these ones even if you could. You would clear them if another mechanic might see them and go chasing a red herring.

[The-Duke]

All of the sensors on the EPIC have the same set ofcolours in the wires... connecting them all together won't do you any favours.

Of course not . Maybe something was unclear. I need the specific combination of the three rotor position sensor wires to the corresponding wires of the EPIC plug's van-side.
By guessing from the sensor's schematics, maybe like this: black -> NR, red -> WB, green -> WG.

The wiring diagram in the service manual unfortunately is inconsistent in at least the pin assignment, and maybe even color codes. For the moment there are too many potential variables to get a clear image - at least to me. However, judging by the fault codes, it can't be totally f*cked up - after all, it's just three bloody wires... , plus the cal. resistor that I don't understand yet why it's not fixed. But that could be a contact issue.

If the issues are resolved then the van will run normally again without any further diagnostic input. The management lamp will stay on for 5 seconds on start up to show there are "historic" codes registered - but that is all.

Thanks, good to know!

Whereabouts are you?

People have had luck using Forscan and a modifid (can buy them as modified off the shelf) ELM327 for reading fault codes on EPICs

Between Stuttgart and Ulm in Germany. The van currently is at a shop that can read the codes, but this is some kilometres away. I've tried a Ford-modified reader (one with a switch) with Forscan before, but without any luck. I think the 1996 model is quite special here. With later ones it seems to actually work from what I've read so far.

I'll have to take a more systematic approach in the next days: Measuring the voltages at WB, WG, NR should help to identify +5V/GND supply and the signal wire on the van side. Another resistance measurements on the sensor should reveal the internal assignment to sensor and temp-compensation. After putting those pieces together I hope to get a better image on the situation and how the stuff belongs together. After all, I cannot totally rule out the possibility that sensor is actually broken, even though I think that in this case the readings I already got would be much more different.

Someone kindly offering their services would need to unplug their EPIC pump round connector and characterize each connector pin in question, the resistance each one has to chassis ground. Would be a bonus if note the wire color too.

Yes. At least a good start would be to know for sure the color-code / pin number combination.

There's something peculiar with the brown-red wires. The mechanic may had transposed the brown-reds.

Yes, something I also already suspected. I'll check this by measuring resistance between the different NRs / chassis ground.

Fault codes generally clear by themselves and turn off the check engine light, once the condition that caused it has been removed. Stored fault codes that don't turn the light on are clearable but there's no point clearing these ones even if you could. You would clear them if another mechanic might see them and go chasing a red herring.

Thanks for confirming!

Have a nice weekend! I'll post an update as soon as I have any news from the van.

Cheers
Sascha

[marcrbarker]

By guessing from the sensor's schematics, maybe like this: black -> NR, red -> WB, green -> WG

Something that's just occurred to me. I'm just checking, apologies if you knew this. Do you know the symbols "NR" "WB" "WG" mean "brown-red / white-black / white-green" ??

I see a two-element transposition here, (involving 'NR' & 'WB'.)

2021-09-25 13.02.46.jpg

[The-Duke]

Yes, I know these abbreviations, the codes are explained in the service manual. But thanks for checking anyway.

What I meant was the internal wiring of the pump. The sensor wires are single-coloured: red, black and green. That's what I wanted to show with the photo above. The other sides in the photo are extension wires, with randomly chosen colours, to complicate things to a maximum...

If I mixed up the codes somewhere I probably made a mistake. I'm starting to get blind by staring at the bloody manual and my current measurements in the hope to see the solution...

[marcrbarker]

20210925_150200.jpg

20210925_150820.jpg

2021-09-25 15.11.15.jpg

I'm sorry I forgot the actual pump wire colours don't correspond with the harness colours!!!


Resistance readings axial sensor. Red to green 59 ohms
Red to black 343 ohms
Green to black 285 ohms

With pump disconnected and ignition on
Brown-red = 4.5 V
White-green 5.0V
White-black = 4.5V
All with respect to battery negative.

And now for the kicker......
The other brown-red wire of the other sensor
Brown-red = 0V

[The-Duke]

Yay!!! You didn't dismantle your pump to make those fotos, did you?? This is awesome, it confirms my suspicion that two of the soldered wires were transposed.

However, it probably also confirms that I simply did a bad job re-connecting them (or making some other stupid mistake), otherwise it would have simply worked... Or actually the both brown-red wires (one belonging to the cal resistor) have also been transposed. I'll find out next week.

Can't wait to test this out... you made my day!

Cheers
Sascha