jpete Posted May 26, 2010 Share Posted May 26, 2010 2001 F350 with 7.3 arrived with cranks won't run. Code p1668 ODDTC & P1670 CMDTC. Followed code flow chart. Replaced IDM truck started. Ran approx 1000 miles. Broke down again cranks, won't run. Had p1668 again. Followed code chart, also did volt drop test on all power and ground circuits for IDM and PCM. Ohm checked injectors 3.3 - 3.9 ohms. Replaced IDM. Truck started. Ran about 900 miles. Truck towed to shop 3rd time. Cranks, won't run. Code P1668 OD, P1670 CM present. Swapped IDM from another unit, truck started. We can't figure out what could be burning out the IDM. Any insight would be greatly appreciated. Thanks Jack Peterson Fleet Manager for The Craig Group Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted May 26, 2010 Share Posted May 26, 2010 What brand are the IDMs and where are you getting them from? I can't remember seeing a physical problem causing repeat IDM failures. Quote Link to comment Share on other sites More sharing options...
jpete Posted May 26, 2010 Author Share Posted May 26, 2010 Using only Ford parts from Chapman Ford. They warrantied the second IDM. I doubt they will another. We have replace IDM's on other trucks successfully with no comeback. Could something in the PCM cause the IDM failure? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 26, 2010 Share Posted May 26, 2010 Bad batteries, poor grounds... Quote Link to comment Share on other sites More sharing options...
jpete Posted May 26, 2010 Author Share Posted May 26, 2010 Power and Grounds were my first thought. Batterys were load tested and confirmed alternator output. We volt drop tested every ground and power circuit we could find on the IDM and PCM plugs. We also removed and cleaned any ground connections on the fender and firewall. I am really stumped on this one. I don't want believe I got 2 bad IDM's from Ford. Although anything is possible. Am I missing something obvious? Quote Link to comment Share on other sites More sharing options...
blown99 Posted May 27, 2010 Share Posted May 27, 2010 Check for an A/C output from the alternator? Alternator spiking high? Quote Link to comment Share on other sites More sharing options...
jpete Posted May 27, 2010 Author Share Posted May 27, 2010 Did not check for AC volts. We did load the alternator to over 105 amps @ 12.2VDC and diodes showed good with AVR. What would be too much ACv? Did not consider spiking DCv. Could a code be generated for excess DC voltage? Quote Link to comment Share on other sites More sharing options...
joshbuys Posted May 27, 2010 Share Posted May 27, 2010 AC Voltage should not exceed 0.5VAC. Not sure how high it would have to get to take out the IDM though... Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted May 27, 2010 Share Posted May 27, 2010 Most charging systems put out only .02-.05VAC (yes, .02V) at low output. That .5 spec is older than I am and really outdated. I sent a new IH back to the dealer when it was putting out about .4VAC and they replaced the alternator. As much as I emphasize clean power, my gut feeling is that you have a bad run of IDMs. I've seen lots of bad power to IDMs through relay pitting and power supply problems and never saw an IDM damaged by it. When I had the shop I would frequently see a bad run of parts from one supplier, even OE. If I had two in a row bad I always changed suppliers. Maybe you guys will prove me wrong on this one. If you know the guy, swap a used IDM into his truck from (another of his trucks?) something and see if it lasts. Good Luck! Quote Link to comment Share on other sites More sharing options...
jpete Posted May 27, 2010 Author Share Posted May 27, 2010 I have another truck that I borrowed the IDM & PCM from. I installed them in the problem truck. Passes SCAN/ROAD test. So I have a bad IDM and a working PCM on the bench. If the truck doesnt come back I'll assume the PCM? I hate to not find a cause. We have towed this thing 3 times. This is a fleet vehicle. We have a full service shop to support the operation. If I had to bill a retail customer for the diagnosis time alone, it would be thousands of dollars. And it may not be fixed yet. We performed a poke and hope repair. Quote Link to comment Share on other sites More sharing options...
jpete Posted May 27, 2010 Author Share Posted May 27, 2010 Bruce, Keith, Blown, Josh, Appreciate very much your taking the time to reply. Jack Peterson Quote Link to comment Share on other sites More sharing options...
Aaron Posted June 3, 2010 Share Posted June 3, 2010 Has the truck come back yet? Did your swap fix it up? I'd see if the supplier would come good with some cake for your diagtime. Quote Link to comment Share on other sites More sharing options...
jpete Posted July 26, 2010 Author Share Posted July 26, 2010 Well the truck came back with the IDM bad. This IDM was a removed from a known good working vehicle. We did find the connector at the IDM full of water. Quote Link to comment Share on other sites More sharing options...
lraffe1 Posted July 27, 2010 Share Posted July 27, 2010 I had an e-van at my dealership going through idms every 3 months or so. When I got it it was on 4 idm. I checked every voltage, ground and inj circuits. I could never find a problem till I drove it in rain or maybe it just sat in ran can't remember exactly ist been awhile. I installed a ran hat maid from an old inner tube, which I think was a suggestion from someonr here, and it has not been back. However, I don't remember hearing of super dutys doing this. Also, not real sure how u could protect idm this way with how idm is mounted in fender well. Quote Link to comment Share on other sites More sharing options...
BrunoWilimek Posted July 30, 2010 Share Posted July 30, 2010 Any chance the water seal in the connector is damaged? I had a couple of Lincoln LX's(yeah I know it's not even close to a diesel e-van)that would have a "global open" event every time it rained. Global open means all the windows and sunroof open to allow the vehicle to vent on a hot day before you get in. This is normally triggered by the remote keyfob. The main connector for the module that controls the global opening is in the driver's door. If water got in the connector(like when it's raining), a global open event was triggered. A TSB or SSM was supposed to address this issue by filling the connector with silicone dielectric grease to prevent the entry of water. Another tech did this on one of the cars, thinking the problem was solved. The next time it rained, we got the car back with a sodden interior, again and an irate owner. I inspected the connector and found that there were several unused terminals in the connector that had plugs inserted in the hole where the wire would have been, had there been one. The plugs were forced out of the connector seal by the pressure exerted by the grease. This allowed water entry through the now empty holes in the seal. I resealed the connector properly and the vehicle has not been back for this problem since. If water is getting in the connector, it must be coming from somewhere, right? Solve the puzzle of where it is coming from and your repeat problem will likely go away. Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted August 1, 2010 Share Posted August 1, 2010 Yea thats like having stiff steering on a town car when it rains or just after a bad rainstorm, when the vaps module drys up all is well. Replace windsheld and stiff steering concern gone. Or 4x4 lt. on expedition flickering-same scenario. Quote Link to comment Share on other sites More sharing options...
GRAMZ Posted September 22, 2010 Share Posted September 22, 2010 hey just wondering what you found with this truck ?i have an 03 7.3l same concern but truck runs o.k for me ,koeo p1668 on demand p1670 continous,after truck runs.customer complaint of stalling.but will restart, have tried known good idm ,attempt clear codes reset kam p1668 still there ,load test pwrs and grds to idm load test communication wire from idm to pcm o.k ,suspect pcm ? just not sure why truck runs o.k for me with these codes? Quote Link to comment Share on other sites More sharing options...
jpete Posted March 31, 2011 Author Share Posted March 31, 2011 Turns out the problem was an intermittant shorted injector that finaly appeared as a miss while road testing. We installed 8 injectors from a used engine and have had no other issues. Quote Link to comment Share on other sites More sharing options...
lmorris Posted March 31, 2011 Share Posted March 31, 2011 They can be a bugger that way. And there is no way to pinpoint which injector is the culprit in most cases. Quote Link to comment Share on other sites More sharing options...
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