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Posted: 10/24/2010 8:55:01 AM EDT
OK here is the long and short.

It is a 1985 E-350 Ambulance. It has a 88 or 89 f-350 7.5l EFI engine and auto transmission in it. I did not do the swap.

alternator was bad. It was a leece Neville 130 amp. I switched to a
large body motorcraft with an external regulator. Upon hook up I ended
up hooking the two ecm black/green wires to the positive terminal on the
alternator. ( i know Stupid me). I have the truck running now but i get
codes 23 and 34 (tps and EGR i believe) when i just turn the koeo code
check prior to first start. then once i start it i get a lot of codes. I
tried to drive it but it acts like it is in limp mode. most codes seem
related to sig rtn and maybe vref. I do not get a bad rom code though
(although I got it once but it disappeared).


I do have an Actron tester i can hook up that gives codes and descriptions.

is now charging. the starting solenoid has two large opposing posts and
a S and I small terminals. It is not a stock ford solenoid.
Link Posted: 10/24/2010 12:04:18 PM EDT
I just fixed a 90 Bronco setting the same dtc strings about a month ago. All 3 capacitors had exploded. I suspect he hooked up the battery backwards after he wrecked it and fixed it.

It's a long shot not being there to see the vehicle myself,  but take out the processor , disassemble it and check the capacitors and board very carefully.

I fixed an 89  mustang doing the same thing about 6 months ago, dude hooked up the battery charger in reverse for a second, and the processor lost the internal ground. The fix for that was to run a ground from the tps to the body ground.

The sensors(you will need a wiring diagram) can be tested for vref and ground easily with a dvom. It is possible one is shorted to ground, knocking out the reference regulator.

Good luck.
Link Posted: 10/24/2010 4:49:31 PM EDT
any more details or a process to accurately determine this? I have a dvom and also actron computer and actron sensor tester.

I have the tools but the process and methodology is what i lack in this situation.  It has been awhile since i had to trouble shoot eec-iv.
Link Posted: 10/24/2010 6:47:23 PM EDT
Start with the tps and egr. both are simple 3 wire sensors. backprobe with them plugged in, key on.

One wire should be 5 volts(reference)

One, ground(signal return)

One, sensor signal. see below.

egr should be in the neighborhood of .5 volts, pull a vacuum on the valve to open it and the voltage will rise.

Tps should be .95 volts, open the throttle and it should linear increase to 4.5 volts.
Link Posted: 10/25/2010 1:17:11 PM EDT
Finally had some time to pull codes:

KOEO Code 23

TP Sensor out of range during self test

KOEO Code 34

EVP Sensor voltage above closed limit.

KOEO Code 10

KOEO Code 22

BP/MAP Sensor out of range during self test.

KOEO Code 35

EVP Sensor voltage above max limit.

KOEO code 51

ECT Circuit above max voltage

Deg -40F Indicated

KOEO Code 53

TP Sensor above max voltage.

KOEO Code 54

ACT/IAT/VAT Circuit above max voltage

Deg -40F Indicated
Link Posted: 10/25/2010 1:55:14 PM EDT
Voltage results from the harness to evp sensor sensor unhooked:

Pin 26 vref orange white 3.5 volts to ground jumped around

Pin 27 evp brown lt green 24-38 mv 5 ohms to ground

Pin 46 sig rtn blk white 3.8 volts to ground jumped around
Link Posted: 10/25/2010 3:11:29 PM EDT
pin 46 was fried on computer. I tried resoldering it but no dice. I may try a resolder in the morning there is no processor to remove on this 88 so i hope the chip isnt hosed now.
Link Posted: 10/25/2010 3:17:34 PM EDT
If the processor board is bricked, which it sounds like it may be, the only option is to replace the entire assembly.

What year and model is the processor from? I know in the OP you said that it was engine swapped, I would like to look at the pinouts for the components.
Link Posted: 10/25/2010 3:26:55 PM EDT
IT IS AN 88 OR 89 F-350 AUTO with a 7.5L Engine processor is:


EFI-SD21E E8tf-12a650-BL1B
Link Posted: 10/26/2010 6:05:41 AM EDT
This is after scrapping the black stuff off. there is no continuity between the pins.

Computer label:

Link Posted: 10/26/2010 6:07:00 AM EDT
I have soldered a wire to the pins. I now have continuity from the harness to the farthest pin that i soldered.
Link Posted: 10/26/2010 6:36:32 AM EDT
[Last Edit: 10/26/2010 8:04:29 AM EDT by 4bangin]
hooked it up. no longer able to get codes from actron. unhooked actron and truck starts but same issues. ecm toast now? also the resistor from the sig rtn on board has like 200 ohms is that correct?
in addition with the actron hooked up (it is a digital reader with display) the fuel pump runs continuously in KOEO.

ETA: pretty sure it is fucked. ordered new one. 137.99 mutherfucker.

Link Posted: 10/26/2010 10:01:06 PM EDT
[Last Edit: 10/26/2010 10:07:14 PM EDT by AnticitizenOne]
You went to a lot more trouble to fix it than I would have, I salute you.

Sorry it bricked, but you did find a pretty good price on it.

Usually in the field, I take it apart to verify the failure, then obtain a replacement, then thoroughly check the vehicle for possible causes of the failure, but very rarely do I try to repair a ecm board, even on my own, with the exception of replacing a leaky capacitor.

Link Posted: 10/27/2010 7:48:57 AM EDT
$145 later new computer is in, KOEO passed except for IAT ECT since i
did it cold, and got 11 pass. ran it for 15 minutes around the
neighborhood came back did a KOER no codes except for EGR stuck closed,
which i know about. I would rather have it stuck closed then open i
guess. Will get a replacement EGR from pick n pull in the future
sometime, but for now it purrs like a kitten. Thanks for the help.
Link Posted: 10/27/2010 4:26:42 PM EDT
The egr is directly coupled to the spark advance. Lack of egr movement will cause sluggish performance and weak fuel mileage.

Glad you got it fixed without too much trouble
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