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Discussion Starter #1 (Edited)
Hey Ya'll. My truck quit on me this morning. RPMs bounced about while cruising at about 50 mph, lost power, alternator gage jumped about, briefly straightened up then died. Now when I turn key I get no "wait to start" light, no check engine light, the ABS comes on briefly, the battery and break light remain on. The engine turns over but without glow plugs it aint cranking. I checked the glow plug relay and it has power to one of the big posts, but when I turn the key there is no power to any of the other posts at all....I replaced the fuel pump and IDM relays, relays 1 & 2 respectively. Still no "wait to start light". My friend hooked his code reader in and got a message "no response". His reader has worked in the past and worked on his truck today. Please tell me the PCM or IDM are not dead. Need help bad. this my only ride and nobody around here has a clue. Thanks.:ford:

Could the glow plug relay be bad and responsible for the "wait to start light not coming on?

Okay found the 30 amp fuse to the glow plug controller blown. Replaced it and the engine cranked and ran for about 20 sec and died. Fuse was blown again. Also found the diode for the powertrain control system relay coil in position 12 is no good. Where is the powertrain control system relay coil?

I read where one individual had something similar happen and found the heating element in his fuel bowl loose and thats what shorted out his fuse. If thats the case do you remove it or replace it.
 

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The fuse that blew was probably fuse #22. You need to disconnect the fuel heater (which has probably shorted) which is on the driver's side of the fuel filter bowl about halfway down. It is a one-wire connection with a funky-looking plug. You can disconnect it there, but I usually prefer to disconnect the fuel heater by draining the filter bowl and removing the lid and filter and then unplugging the small spade connector on the inside of the fuel bowl (the wire connects to the plate with the bare wire heater element that usually breaks loose). For some reason I always have a hard time getting the external connection off with out damaging the part on the side of the fuel bowl (a $45 part). Replace the fuse again as it also powers the computer! Cheers!

Added in edit: How did you determine the PCM power relay coil was bad? The power for that coil comes from fuse #22 through the PCM power diode (so depending on how you attempted to check the continuity of the coil, the diode could have caused a false open.
 

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Discussion Starter #3
Thanks for your prompt help Patrick. I will try it in the morning. Pretty cold out now. Just out of curiosity.....where is the "powertrain control system relay coil" that #22 30 amp fuse and # 12 diode are associated with? Can't find anything online. Thanks again.
 

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Sorry I wasn't reading my EVTM (Electrical and Vacuum Troubleshooting Manual) correctly! The diode is in position 12 (I missed that) and the PCM Power Relay is the relay on the right of fuses 13 & 14 (standing at the driver's fender looking at fuse box). The coil would be terminal 89 and 86 on the relay if they mark them. Cheers!
 

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Discussion Starter #5
You were right. #22 was blown and I chk'd continuity on the diode and got none so I figure its bad too. I am waiting on the diode to come in from Atlanta in the morning. I also replaced relays 1 and 2 as you noted. So the "powertrain control system relay coil" are relays 1 and 2? My owners manual doesn't show 89 and 86. Thanks.
 

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The PCM Power relay is relay 1 while the IDM Power Relay is relay 2. Each relay should have 4 terminals, 2 for the activating coil portion of the relay and 2 for the switch portion of the relay. With the relay out of the fusebox, there should be continuity between 2 of the terminals (the coil). Once you find those 2 (unless the coil is bad), the other two will be the switch portion. If you apply 12V to the coil terminals you should hear the switch "switch". With 12V on the coil, there should be continuity through the switch contacts. If you're trying to check the diode with a continuity tester, try it with the leads one way and if you don't get continuity, switch the leads around the other way (diodes only pass current in one direction). Cheers!
 

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Discussion Starter #7
Thanks Patrick. I checked the diode yesterday in the same manor you suggested and didn't have continuity in either direction. Ordered 2 lastnight and they should be here in a couple of hours. Going outside now to take care of the wire element in the fuel bowl. Chilly out this morning. Have agreat day. I'll update soon.
 
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