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Troubleshooting P0401, P0340, P0443 but no CEL


crowfather

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I recently purchased a '96 Ranger for cheap. I knew it had a few issues but I don't mind wrenching. I took care of the obvious stuff already. Rear wheel bearings and seals since they were leaking (required a new axle shaft), rear brake job, front outer tie rod ends and adjuster sleeves, headlamp lenses were cracked. The rest of it looked pretty good if dirty, it was a farm truck. Ran rather well and there wasn't a CEL so I didn't look at the engine too much. However, the odometer didn't work and the turn signal indicator would only illuminate when turning left. Well I found this forum and the article with how to fix the worm gear. While I had the instrument panel out I decided to replace all the bulbs as a pre-emptive measure. It wasn't bad, but I don't feel like making a habit of pulling the dash apart.

CEL: After reassembling I confirmed that the odometer was now working, but the bulbs didn't fix my turn signal problem. The panel back lights work just fine, and I can see all the gauges and their backlit symbols. However, when using my scan tool to check for codes after a rough idle morning I found three codes (P0401, P0340, P0443). There was no CEL displayed, I just got lucky. Now I wonder if the panel circuitry has some issues since I have no CEL, and the "brights" symbol doesn't illuminate when I turn on the brights at night. Do any of you know how to hunt this one down?

P0443: I found that the tubing running from the intake manifold to the purge valve to be severely dry rotten. Additionally the line running from the purge flow sensor to the purge valve itself was gone, and the purge valve was dangling down below the battery disconnected from the vapor canister. I bought some rubber tubing from nappa and had it all connected back up. I suspect this will go away with some driving now.

P0340: I found where the cam position sensor is, but after reading a bit here I am unsure if I should change the cam synchro at the same time. I am not sure what the mileage on the truck is because of the odometer issue, was stuck at 200,500 since before previous owner, but it may be a good idea to replace both at this time. Could the pigtail/wiring harness cause this issue? Maybe that needs to be swapped as well? Basically I am not sure on this one since what I've read points to multiple spots other than the CMS. One place suggested a bad timing belt, for example.

P0401: Ran into a snag when troubleshooting this one. I went to pull off the EGR valve to check if it was plugged up, and ended up shearing off one of the bolts. Looks like a stainless steel bolt in the aluminum housing. This is causing me issues presently so I haven't gone further with this yet. I ended up drilling through the bolt and I will just be putting a nut on behind the mounting spot. This was the right side EGR bolt that goes through the mounting point on the manifold. Turns out that the EGR is not clogged, not sure if it works properly yet though. If it is not the valve, I read it could be the EGR pressure feedback sensor. If so, how would I go about testing this?

Thanks for listening to all my issues. Any advice or direction is welcomed.
 


franklin2

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Those feedback sensors are famous for going bad. I am not sure I would worry about it. It will not affect how it runs, the computer may just retard the timing slightly when it finds out the EGR is not working.

Interestingly, according to these diagrams the speedometer and the MIL lamp are both fed by the same fused leg in the instrument cluster. Does your oil pressure gauge work?
 

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crowfather

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Ford Ranger
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Thanks franklin. It definitely ran fine which was why I hadn't suspected anything. Yes, oil pressure and all gauges work just fine.
 

crowfather

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Ford Ranger
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To make matters worse, this morning I cracked the aluminum intake manifold when trying to get that bolt removed. Woof.
 

crowfather

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1996
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Ford Ranger
Transmission
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Bump

Does anybody know anything more about the instrument cluster issue? Would it be possible to just replace one or two of the clusters? I know the cluster for the speedometer and tach works.

Is there a way to troubleshoot the cluster out of the vehicle?
 

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