Intermittent ECM failure 330 hp CAT

[RobertDavis]

2003 Fleetwood Discovery 39S with 330 HP 3126? Caterpillar engine. I am in a pickle. All help is appreciated. Since September, It has quit 7 times. It's been to 3 Caterpillar shops in 3 states, one Freightliner shop and one independent shop. With tows and "repairs" I am $14,250 (almost half the value of the coach) into this and it is still not fixed. Currently it is in Georgia at a Cat dealer shop for 3 weeks.

First break down was idling at a rest stop. The symptoms was no start with fast turnover unless a shot of ether was used. Obviously no fuel. Was diagnosed as a bad ECM as evidenced with no ECM recognition when connected to Computer diagnostic port. Odo read 1888888, trip read 8888 and voltage pegged to the left. There was 12.5 volts at the chassis batteries. The independent shop told me that the local Cat shop sold and programed the new ECM. They told me that they took it back 3 times before it worked. When I picked it up after a month, the odo was 000000. I took it to the local CAT dealer to finish the ECM set up. The CAT guy laughed and told me the 3 trip back to them story and the rest of the story was he sent one of his techs to the independent shop and tightened the 70 pin harness connector bolt and it fixed it.

Next breakdown was 250 miles later at highway speed. Same symptoms. Towed to a different CAT shop. They saw the same symptoms but ECM was recognised by removing the 70 pin connector and connecting the computer directly to the ECM. They reconnected the harness, cleaned one battery terminal and sent me on my way.

3rd breakdown was 150 miles later at highway speed. Towed on a Saturday after hours to Freightliner. Called them on monday morning. They told me they couldn't help me because it had a CAT engine. It started. I picked it up and drove it to the third CAT dealer. I left it and flew back home to FL. They replaced the switch wire to the ECM along with 2 positive and 3 negative wires to battery.

I flew back to GA to pick it up. Made it 45 miles and it quit pulling into a camp site. Same symptoms. After 2 days of trying I got it to start by turning the ECM 70 pin connector screw a quarter turn.

4th breakdown was 10 miles later. I turned the same screw another quarter turn or less.

I made it to the storage place and then flew back home to FL.

5th breakdown was when I drove back to GA to take it back to the CAT dealer that replaced the wires. It quit in the storage lot 50 yards from parking spot. Now the ECM screw is really tight. I turned it ever so slightly. It started. It quit 30-40 miles later enroute to CAT. This time it was only 5-6 seconds while moving 60 mph. Cat tapped out the threads in the ECM where the harness connects. Said it 100% will fix my problem.

6th breakdown was 30 miles leaving CAT. It was a short one as before and I made it to a truck stop parking lot.

7th breakdown was at idle in the parking lot. You guessed it, I tried to tighten the screw. It started and I drove it back to CAT where it currently is.

[Cat]

Originally Posted by RobertDavis

2003 Fleetwood Discovery 39S with 330 HP 3126? Caterpillar engine. I am in a pickle. All help is appreciated. Since September, It has quit 7 times. It's been to 3 Caterpillar shops in 3 states, one Freightliner shop and one independent shop. With tows and "repairs" I am $14,250 (almost half the value of the coach) into this and it is still not fixed. Currently it is in Georgia at a Cat dealer shop for 3 weeks.

First break down was idling at a rest stop. The symptoms was no start with fast turnover unless a shot of ether was used. Obviously no fuel. Was diagnosed as a bad ECM as evidenced with no ECM recognition when connected to Computer diagnostic port. Odo read 1888888, trip read 8888 and voltage pegged to the left. There was 12.5 volts at the chassis batteries. The independent shop told me that the local Cat shop sold and programed the new ECM. They told me that they took it back 3 times before it worked. When I picked it up after a month, the odo was 000000. I took it to the local CAT dealer to finish the ECM set up. The CAT guy laughed and told me the 3 trip back to them story and the rest of the story was he sent one of his techs to the independent shop and tightened the 70 pin harness connector bolt and it fixed it.

Next breakdown was 250 miles later at highway speed. Same symptoms. Towed to a different CAT shop. They saw the same symptoms but ECM was recognised by removing the 70 pin connector and connecting the computer directly to the ECM. They reconnected the harness, cleaned one battery terminal and sent me on my way.

3rd breakdown was 150 miles later at highway speed. Towed on a Saturday after hours to Freightliner. Called them on monday morning. They told me they couldn't help me because it had a CAT engine. It started. I picked it up and drove it to the third CAT dealer. I left it and flew back home to FL. They replaced the switch wire to the ECM along with 2 positive and 3 negative wires to battery.

I flew back to GA to pick it up. Made it 45 miles and it quit pulling into a camp site. Same symptoms. After 2 days of trying I got it to start by turning the ECM 70 pin connector screw a quarter turn.

4th breakdown was 10 miles later. I turned the same screw another quarter turn or less.

I made it to the storage place and then flew back home to FL.

5th breakdown was when I drove back to GA to take it back to the CAT dealer that replaced the wires. It quit in the storage lot 50 yards from parking spot. Now the ECM screw is really tight. I turned it ever so slightly. It started. It quit 30-40 miles later enroute to CAT. This time it was only 5-6 seconds while moving 60 mph. Cat tapped out the threads in the ECM where the harness connects. Said it 100% will fix my problem.

6th breakdown was 30 miles leaving CAT. It was a short one as before and I made it to a truck stop parking lot.

7th breakdown was at idle in the parking lot. You guessed it, I tried to tighten the screw. It started and I drove it back to CAT where it currently is.

Ok since it seems every time you touch the 70 pin connector it runs for period of time. You need to do what the manual calls a 10 pound pull on the each individual wire that is plugged into the connector to ensure the wire is still crimped positively to the wire terminal. This is done while the 70 pin connector is still screwed to the ecm. You pull the wire directly away from the connector --- 10 pound pull.
If ok then remove the 70 pin connector. You then need to have new pin or male wire connector it should be the same size as the pins/male sticking out of the ecm that goes into socket/ female 70 pin connector. These terminals are standard Caterpillar sizes that are available in CAT connector kits. You take the new pin/ male terminal and push it into each 70 terminal hole it should be a good firm push in and then pull out. It should feel the same in each hole. If you find one terminal hole that is a easy or loose in and out the terminal will have to be replace. Hope that helps Let us know what you find or fixes your problem. Good luck Safe Travels

[RobertDavis]

Thank you. I will call the Cat dealer tomorrow and suggest these tests.

[Cat]

The ten pound pull is a normal test procedure, unfortunately people forget the basic stuff. The pin is more unusual test procedure -- but I have seen the terminal problem ( where the female terminal does grip the male pin. They may poopoo this test but it is critical todo. You problem is also very unusual. Again good look and let us know what progress you're making.Safe Travels

[RobertDavis]

Thanks for the help. Cat replaced the ECM again and the 70 pin connector and all of it’s female pins. 450 miles no breakdowns. Mileage went back to zero. Took it back to cat. They say this third ECM is bad and won’t take the correct mileage. Thinking of leaving alone.

[Cat]

Originally Posted by RobertDavis

Thanks for the help. Cat replaced the ECM again and the 70 pin connector and all of it’s female pins. 450 miles no breakdowns. Mileage went back to zero. Took it back to cat. They say this third ECM is bad and won’t take the correct mileage. Thinking of leaving alone.

First congratulations on getting it fixed.

But
That is not correct the miles and hours can be reentered with a CAT password. That's not a big deal. You cannot enter a value that was lower then the previous values. So can't lower your mileage or hours. But as much trouble as you have had and sense there are no warranty worries. Id leave it alone. Safe Travels

[lpasekof]

Was the ECM and 70 pin connector the final resolution? I have an almost identical chassis, year, motor etc. I'm having a very similar problem. Taking it in next week but I have to go to an independent shop as my rig is now too old for the Freightliner dealer to work on it.

If this (most likely the 70 pin connector) was the final resolution I'd like to be able to suggest it to them.

[RobertDavis]

Originally Posted by Cat

First congratulations on getting it fixed.

But
That is not correct the miles and hours can be reentered with a CAT password. That's not a big deal. You cannot enter a value that was lower then the previous values. So can't lower your mileage or hours. But as much trouble as you have had and sense there are no warranty worries. Id leave it alone. Safe Travels

The Cat dealer said the miles wouldn’t couldn’t be entered and stay because the new ECM was bad. They replaced it again. Finally fixed.

[RobertDavis]

The final fix was another ECM. It was replaced 3 times. It seems CAT only had rebuilt ones.