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1989 F350 Ex Cab dually 7.3 IDI Turbo, 1997 F350 Crew Cab dually, 2001 F350 Ex Cab Dually 4wd
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Discussion Starter · #1 ·
I have an issue with my 97' F350. It started getting colder finally along the Gulf Coast of Texas where I am at, I went to crank my truck and noticed the wait to start light did not come on. I didn't think much of it so I tried to start the truck and it would turn over fine but not try to hit or crank. I popped the hood to start checking things and realized I had a rapid clicking sound coming from the power distribution box. Upon checking it was the IDM relay. I checked the voltage that brings the relay in and it was about 9.5v. I started checking the forums to see what was up with it and I started trouble shooting. I checked fuses and relays all were good, upon reading more forums I found that it could be the glow plug relay. With the IDM relay clicking it was not coming in either. The glow plug relay was looking old and tired anyway so I changed it. It did not fix the issue. I started checking the ground points and using jumpers to check grounds, that all seemed good. I started jiggling wire harnesses and there was no change there. Then I did something that in retrospect might have been foolish. I had the key on, the relay was clicking away and I accidently crossed the two small posts on the glow plug relay. The IDM relay locked in and the truck cranked and ran fine, if I unplugged the jumper it would die. There was an instance before that though where I was trouble shooting and I pulled out the PCM and re-installed it and the truck ran, I thought I had fixed it by dumb luck, that only lasted a day though. I had another PCM laying around that I plugged in and still the same thing. My question is am I completely missing something or has my PCM gone out. Been a Ford man since I started driving and have wrenched on these for many years from IDI's to Powestrokes. I use them for farm trucks because they are tough and economical. I don't want to give up on this one just quite yet.
 

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Assuming that the batteries are 100% - there is something on the circuit that is dragging it down. Looking at the diagram I have, the power for the circuit that powers the IDM relay comes from the PCM relay (contact side). Is the PCM power relay in good shape? If the contacts are heavily oxidized it could create a "resistor" which would nicely explain the 9.5 volts that you see on the coil side of the IDM relay.

Cj

And Welcome to PSN!
 

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The one time I witnessed this (IDM relay clicking away), it was on my Brother-In-Law's 95. One of the batteries shorted internally. Two new batteries and fixed. Cheers!
 

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What do the battery terminals look like?

 

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1989 F350 Ex Cab dually 7.3 IDI Turbo, 1997 F350 Crew Cab dually, 2001 F350 Ex Cab Dually 4wd
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3 Posts
Discussion Starter · #5 ·
Assuming that the batteries are 100% - there is something on the circuit that is dragging it down. Looking at the diagram I have, the power for the circuit that powers the IDM relay comes from the PCM relay (contact side). Is the PCM power relay in good shape? If the contacts are heavily oxidized it could create a "resistor" which would nicely explain the 9.5 volts that you see on the coil side of the IDM relay.

Cj

And Welcome to PSN!
Thanks for the help CJ. It was that relay. I had never pulled it to check for any corrosion. Sure enough I pulled it out, terminals were corroded and there were dead raspberry ants in the terminals as well. I cleaned it up, put a new relay and it cranked right up. The battery light on the dash that has been on for years even went off. Thanks much for the info, I really appreciate it!
 

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(y) Welcome! Good to hear you found the problem. Thanks for reporting back as well!

Cj
 
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