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98 4.0 ecm repair


dpeterson3

Member
Joined
Feb 19, 2013
Messages
8
Vehicle Year
1998
Transmission
Manual
My 98 4.0 has been throwing a code (can't remember the number now) for bank 1 o2 sensor sluggish. Replace the sensor 2 times, and no change. The ODB-II scope shows no response from the channel (will try to pose a picture later). Yesterday, I put an actual oscilloscope on the inputs to the computer and was able to get a trace that varied between ~0.1 and 0.9 mv as it should. These together lead me to believe the input on the computer has failed. Looking at the computer, I don't see anything obvious such as a failed capacitor (no electrolytics in this one). No burned traces or signs of corrosion. My best guess is the old sensor failed connecting 12v to the input and over-volted the input. This leads me to a couple of questions. 1) Anything else I missed that I should check? No reason I see the ecm should have failed, but nothing else makes sense either 2) Send for repair or buy used? Being the 4.0 4x4 with no PATS, I can only get a 98. Local junk yard doesn't have any. 3) If I send it off, any recommendations on who would be able to work on one of this vintage?
 
I would get another used one. If it turns out to be the problem, great. If not, at least you have a spare now. Sending it off will cost you money no matter if it's broke or not.

You can go to www.car-part.com and most likely find a used computer. Most of the yards will ship and a computer should not be too bad to ship money wise. The first thing you need to do is determine what computer you need. I copied and pasted the different computer selections that car-part came up with when I plugged in a 1998 ranger.


Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, Federal emissions, ID F87F-AMA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, Federal emissions, ID F87F-AMB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, Federal emissions, ID F87F-AMC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, Federal emissions, ID F87F-BTA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, Federal emissions, ID F87F-BUA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-ANA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-ANB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-ANC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-APA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-APC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-BVA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), AT, low emissions, ID F87F-BXA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-AGA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-AGB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-AGC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-AHC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-ALA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-ALB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-ALC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, Federal emissions, ID F87F-BTA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AJA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AJB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AJC
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AKA
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AKB
Electronic Control Module, (RH rear engine, thru firewall), 6-245 (4.0L), MT, low emissions, ID F87F-AKC
 
So I got a used computer from ebay marked as tested, works. I believe it. The truck started right up and ran. However, it has the exact same problem. No signal from the O2 sensor. I guess that only leaves a bad connection between the computer harness and the computer itself. Anyone have experience repairing a single computer pin?
 
So I got a used computer from ebay marked as tested, works. I believe it. The truck started right up and ran. However, it has the exact same problem. No signal from the O2 sensor. I guess that only leaves a bad connection between the computer harness and the computer itself. Anyone have experience repairing a single computer pin?
I was working on a Honda, thought I had this problem, cut the wire, took the panel off the computer and soldered a short wire directly to the computer board and went out under the panel and attached directly to the harness wire. Padded the wire with tape and put the cover back on. It didn't fix it.
 

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