(SOLVED) truck still wont run

[joey_crandall]

I don't know about making it bad but definitely affect it not working correctly.

good to know

i figured this out today, the crank position sensor and ignition control module wiring ties in together and then branches off and connect at pin 1 and pin 6 at the ecu. when i test for resistance between the icm and pin 1 the resistance is 1.7 ohms. but when tested from the icm to pin 6 its at .3 ohms. the when i test from the cps to pin 1 its at .3 then from that to pin 6 its at 1.3. so is there a resistor somewhere in the wiring in between there (the haynes manual didnt show one neither did the fsm from mitsubishilinks.com) or is that a good place to look for a short.

[lush90]

This might be too obvious but there is a pigtail of 2 or 3 wires connected to an eyelet that has to be on one of the bolts that secures the ecm to the cab. I think it is black and it acts as the ground for the ecm. I know it won't start if this isn't attached to the ecm bolt.

[joey_crandall]

hahaha that was one of my issues. along with a disconnected engine ground and the wires that went to the cps were all backwards. i took the ecu back to the shop that rebuilt it before, he said its in the exacts state it was wheni brought it in the first time. but i should have the ecu back thursday.

and the thing about the resistance with them other wires. idk i used a different meter about a week later and the issue was gone.

[lush90]

It's amazing how many times the problem is simpler than you normally imagine. You are going to love this truck once you get it going. Keep us posted!

[joey_crandall]

yeah im stoked. but sadly im done with it if this doesnt fix it this time.

[camoit]

Oh come on man... If you never get it running you will never be able to escape from the old man working you to death. Don't give up. Just make your own harness if you can't find one. I know where to find plugs and sealant.

[joey_crandall]

haha im just hoping it runs this time and i wont have to do anything else. ive had the truck for a year already so it sitting is getting annoying.

[lush90]

Still waiting to hear the happy ending to this thread!

[joey_crandall]

haha well thursday and friday got busy real quick and we have something to look at tomorrow which is in the same city where the guy that rebuilt the ecu is so we will hopefully (again) see tomorrow if it runs.

[bobsnewdirection]

im paying attention to this one, sounds like you are having the same problems as me. hope u figure it out.

[lush90]

Still sitting on the edge of my seat waiting to hear about this machine running!

[joey_crandall]

yeah me too. its been giving the guy problems though. so im waiting to hearb ack from him. ill be sure to kep you guys posted.

[lush90]

So you are waiting for the ecm ?

[joey_crandall]

yeah, hes looking for another core to rip some parts out of. if i dont here from him this weekend imma go junkyard scavenging and hopefully i can get a monty ecu, he said that he can get parts from those to work.

[lush90]

I am running a MM ecm in my '91 which actually has a Diamante 3.0 in it, so I would be surprised if any ecm from an early (90-95 or so) Mitsu 3.0 wouldn't work, at least enough to see if it starts. My guess is the newer ecm's for the same engine will work on the earlier engines, but not early ecm's on new engines.

[joey_crandall]

yeah they guy said he could use parts from almost any first gen sohc 12 valve thats a distributor motor. do you have a ram 50? also i have a 1990 cali emissions ecu so i dont know if that makes a difference.

[lush90]

I have a '90 MM 4x4with the original 3.0 and ecm, both rebuilt. Basically the newer style heads, 95-96, I think, which have a different channels for higher flow, not as prone to cracking. I picked up a '91 MM 4x4 w/ a blown engine, had been run out of oil. I was driving my '90 (175,000 mi.) which I drive daily for work, when at a red light with no warning, it stalled. Cranked but wouldn't start. I pushed it through the intersection and off to the side, checked all the connections I could, everything seemed fine so I called a Mitsu mechanic friend. He told me it was probably ecm. Just before calling for a tow, after sitting for about a half an hour, I tried to start it again and it did. The engine light stayed on but I thought I might as well try to limp it home. It ran really rough, never got over about 25 mph but I got into my drive way. I pulled the ecm out of the '91 and put it in the '90 and it ran perfectly again. I sent the '90 ecm to Foreign Auto Computer in Zephyrhills, FL and had them repair it. Eventually, I found a Mitsu 3.0 6G72 Japanese import engine that some guy had bought but never installed. The Mitsu mechanic identified it as a Diamonte engine, which has higher compression and different oil pan, etc.. He was able to swap some parts from my blown '91 to this engine and install it. It started right up but the engine light stayed on. I swapped the ecm's back so that the originals were in each truck and, voila, no engine light and they both run perfectly.

[joey_crandall]

nice, sounds like a lot of work. i talked to the guy yesterday after my last posting. he said it should be ready today. he also said with my CPS wires being backwards, thats what most likley was causing its problems, and the bad - battery ground. so imma get it today or tomorrow and do a couple other things to button it back up. Just need to rewrap the harness in a few places where we were testing for resistance. probably drop the fuel tank and dump the 1 year old gas out (its a lil over a year old) and hopefully have a running truck by monday.

Oh also if anyone in cali needs there ecm rebuil look up wombles auto parts or car-computers.com in stockton Ca. hes a nice honest guy thats will sit and talk with you and explain things.

[lush90]

These trucks have a fuel tank drain on the bottom rear of the tank, no need to drop the tank!

[joey_crandall]

sweet you just saved my ass from some unessicary work. watch my trucks gonna need a fuel pump.

[camoit]

So is it running?

[joey_crandall]

no still waiting for his call, i hope i can get itrunning this weekend.

[camoit]

Well if you do get it running after this long I think everybody will want some proof, Kind of like digging up the body to check if he is still in the box or not.

[joey_crandall]

hahah oh there wuill be proof.

[MightyMaxNick]

Hey saw your post, i have a 1991 Mighty Max 4x4 v6. My ECU went out at 189,000 if you can I would just try to find a cheep ECU and try that