I started getting a check engine light. It really started when it was very cold -15F and I was idling the truck while I installed chains and hooked up the GN probably 1/2 hour. There was very deep snow and ice and I was only able to go 5-10 mph. I ran for about an hour without exceeding 15 mph . The truck really didn't get warmed up even pulling the trailer and the grid heaters were cycling on and off. The battery votage was under 14 volts most of the time.

I got a CEL and read it with my Smarty. I said O1682 charging system voltage too low. Pluss the P0522 Engine Oil Pressure Sensor/Switch Circuit Low Voltage. The oil pressure sending unit has been acting up for a long time. I have a good mechanical gage.

I just got new batteries the first of Dec so I wouldn't think they would be low.

I cleared the codes and went on my way. Several days later the CEK came on again shortly after startup in -15F again. This time it was accompanied with P0336 Crankshaft Position Sensor A Circuit Range/Performance . There was no performance problems.
I cleared these and the very next time I started it the CEL came on again while I was driving. Right after it came on the tach dropped to 0 for just a second or two then came back. Again I cleared the codes and about a week later the same thing.

So Is the CPS bad or is the low voltage probem causing it.?? I put a new belt on last night and the codes reappeared. Tonight I'll check and verify the batteries are ok.

Also I noticed that the volt meter shows very slow recovery to 14 volts after startup even in 30 deg weather. Everything else seems ok and the motor runs great other than the usual loss of mileage inthe cold winter. No starting problems at all.

One thing I did notice under the hood is that the battery terminals have some coorosion on them. I cleaned them bright when I installed the new batteries in Dec.

Alternator going bad??

 

first make sure all your grounds are good. corrosion or loose grounds will make all kinds of fun stuff happen your alt. slow recovery after start up is more then likely the grid heaters cycling. also your alt. might not be putting out .are you going off the gauge in the cab? have it load tested .and clean all your connections. Electronic hate corrosion.

 

I was also thinking along the ground issues. Tomorrow night I'll take it over to the shop and go over as many grounds as I can find. Start with the battery grounds and clean up the posts again and have the batteries tested over at AZ.

I'll post what I find.

Thanks

 

I suspect you will need to replace your oil pressure sensor. Unfortunately, they are linked to the ECM and once they start making erratic contact the ECM attempts to boost the field current to the alternator because it thinks the voltage is too low. That increases the alternator output enough to overcharge the batteries, will boil the batteries, leads to corrosion on the battery terminals, and creates ghost error codes with other sensors as the system voltage bounces around between 13.8 and 19 VDC and the sensor voltages start bouncing enough to exceed their ranges.

 

Well that's just peachy. I just love this board. There is always someone that has the real in depth information....even if it is bad news. haha

I just happen to have a new oil pressure sending unit and I got a new CPS yesterday. The current one is about 5 years old so it is about time to replace it. I also have Vulcan starter contacts so I can make good use of my shop time since I'll have to take the starter out anyway.

I tried to see the oil press sender on the block but I can't even get a flashlight beam near it so I would guess it will be easier from below. I know where the CPS is.

This little excursion will probably cost me dearly. I trade use of a shop for TIG welding time. I usually get beat 1-3 ...1 hour shop time for 3 hours TIG time. I can see a couple days under the helmet with what he has going. I'll have to ask him if does roll-over-time. haha

I really appreciate all the help I get here.
Thanks again

 

but tig welding is fun........i would rather tig than stick any day!

 

Seeing your posting regarding TIG welding set off another alarm. If you have welded on anything connected to the truck with a TIG unit, it would be a very good idea to have a dealer scan done to read all codes on all control modules.

These rigs tend to fry a connector on the firewall mounted module if even bumped with a TIG unit.

If that has happened, be grateful it was not a common rail rig, as they blow processors like popcorn if hit with inducted field currents from a TIG unit.

 

Thanks for the thought, but for a change I'm ahead of you here.

I'm well aware of the dangers of welding on vehicles. I know there are many guys who do it all the time, I'm not one of them.

I absolutely never ever weld on any vehicle without taking extreme precautions. I will remove the part if at all possible to weld it up. My truck has never had a welder attached to it for anything. I don't even use a charge wire to the trailer batteries preferring to charge them from my generator after unhitching it from the truck.

The closest a welder has been to my truck is to transport it to a site where it is unloaded. Never operated on the truck .

As it turns out my TIG welder is quite clean as far as RF noise. We have run a TV and radio right next to it without any problems while welding with AC high freq on aluminum. It doesen't even affect our RC airplane radios in tests. Actually the magneto in the top fuel Funny car is the worst. It causes all kinds of interference when they are running. There are even problems with the onboard data logger when the motor is running. They go to a lot of effort to insulate this things.

I disconnect the battery and ignition system on my streetrod and remove the ignition box then provide a very clean ground for the welder as close as possible to the weld operation, I also make sure the welder cables do not cross any car wires nor run parallel to them close up. I make a final run thru to make sure there will be a complete connection before I start welding. Nothing like welding on an exhaust pipe only to find all the hangers have done a good job of insulating it from the weld contact. High freq could probably go anywhere in this case. I do a lot of welding on this car as it is my test bed for hot rod items. It's my exception to the rule of not welding on vehicles but it is mine and if it gets messed up I have a good idea what caused it. I also learn what can and can not be done, first hand.

 

It is possible that your alternator may be bad. My 98.5 took a long time to charge up the batteries and never got to the 14 volt level. I found that some of the diodes inside the alternator had failed.

When the battery voltage gets too low all kind of codes can be set and may point you in the wrong direction. It may be wise to reset the codes, charge the batteries and see if the codes come back when the engine is started.

One easy way to test the alternator for bad diodes is by using a DVM to measure the voltage on the field terminals. The field terminals are the small nuts on the back of the alternator with the lower one positive and the upper one negative. With the engine running and the PCM trying to charge the batteries, the voltage at the field terminals should be greater than 4 or 5 volts. If you see 8 or 9 volts, the PCM thinks your batteries are dead and is trying to fast charge them. This condition is what I experienced with bad diodes.

Good luck.

 

Thanks. More good information. Looks like I'll have to wait untill the week end to get in the shop but I sure wil make this test.

 

Well time for an update. Good news and bad news.

Monday night I decided to go pick up the TIG and the little plasma in preparation for the "payback". We gathered up the equipment and headed back to the shop. On the way back I got the usual CEL and the tach again went full scale then 0 then bounced around and finally went to 0 for good. Stopped for fuel and barely got it started. Temp outside was hovering around 0.

Made it to the shop and unloaded the equipment. We got everthing all set up so I decided to call it a day. Went to start the truck in the shop and the starter just barely turned it over. I stopped and checked the batteries with a load tester and they were good (only 6 weeks old). I tried it again and the starter just barely growled again so I ran it down to nothing. I was sure it was shot but to make double sure I hit it again and it lasted about 2 turns and packed it in.

The good news was that at least it quit in the warm shop instead of out in the freezing cold.

The truck was full of ice and salt so it was a real mess to get the starter out. I got it out however. 2 of the nose gear box screws fell out when I lower it down so they probably didn't help matters. I looked into the hole to check the flywheel and it looked good. Since I already had a CPS and an oil pressure sending unit I thought it would be a good time to put them in. The CPS went in pretty easy. The old one looked ok except for a very small bulge. Then I went after the oil pressure sender. Well the OEM one is 1 3/16 and takes a deepwall socket with a very large and deep bore. I didn't have one, just my standard 12 pt 1/2 drive. I reached up with a long large screw drive and a small hammer and knocked off the plastic connector base and chizzled it down to the metal. The regular 1 3/16 socket just fit and I was able to remove the sending unit. Now the new one turns out to be 1 1/16. Again I didn't have a 1 1/16 deep socket that would fit so I took the only 12 pt standard socket I had and cut off the head right at the drive end. I found a piece of chrome moly tube that was just about the exact od of the socket parts and cut off a 1" length and TIG welded them back together. Now I have the technology. haha I threaded the sender in without a problem and easily tightened it up. It's a straight o-ring thread so you don't need a lot of torque.

My son gave me a ride home (3:30) am. My wife teaches school at 2 different schools so I dropped her off and ran over to AutoZone with my "lifetime" starter. The gal tested it and it said good but there is no load test done. She wasn't going to give me a new one an warantee so I got the mgr over and told him the story of the dead starter. After he looked up my account and saw 5 batteries and about $500 of parts over just the last year he ok'd the replacement. This is the 3rd one on lifetime from AZ, gotta love AZ. Anyway I got the new one.

The starter went in a lot easier than it came out. I found that I could use a short a wobble extension and a medium standard extension and a flop head ratchet with a 10mm socket to get at the top bolt. It only fits if you screw the bolt in most of the way by hand. I got everything buttoned up and let the truck down off the stands. I'm very paranoid about working under the truck as I have had one stand shatter a couple years ago. I use double stands (4) and leave the jack under the cross member.

Earlier after testing the batteries I hooked up the charger and charged the batteries just to make sure they were full.

The good news is that the truck started almost instantly. It always feels good when you solve the probem. I cleared the codes and left for the days rounds.

Today it was -5 F and the truck had sat out for a full day. 2 cycles on the grid heaters and it started right up. The idle up and 3 cyl warm up worked perfect. The alternator seems to be ok, it charges at about 2 needle widths past 14 where it normally does in cold weather. I'll do the diode check next week as I have to move starting tomorrow. I Checked codes again tonight and none are showing after 2 days. Let's hope it stays that way.

I want to thank you guys for the help and insight to the problems.

 

Thanks for giving us closure. It's good to hear the problem is solved.

With the voltage readings you see, I would not worry about the diodes being bad.