Ok, The lights flash 5 times then go off. the 4X4 high was working correctly up til now. We were using the high tonight, I went back out to move the truck and noticed the lights flashing. I have and actron OBDII reader (CP9135), I plugged it in but no codes were present. Not sure how to read the codes from the flashing lights. The truck has 86000 on it looks like new and runs great! I have recently changed the MAF, as well as all the recalls that I am aware of IE tensioner , TB. I change the oil regularly and use full synthetic with a K&N oil filter. I am very fond of this truck even though people call them Exploders, I have not had any problems, Til now. But I assume that this may just be a sensor problem, but nonetheless I am still frustrated over it.
Ok, I have been over the truck, No blown fuses, No codes - all systems state "ready". Plugs and harnesses at or near the transfer case look good. No debris on undercarriage. AWD seems to engage, I took er out on a snow covered hill, the front tires engaged as normal. No strange sounds emenating from the vehicle. Called dealer, say's bring it in we'll take a look at it, YEAH RIGHT! I can look at it just fine thanks! It the fixing part that scares me, I don't have any extra arms n legs to give out right now. I could fix it myself, if only I knew what it was thats broke! I also don't want to buy sensors and such using the trial and error method. Is there a sure fire way to troubleshhot this problem. ] Searcher1 AKA Rich
Well, perhaps understanding the system a bit will help. First of all, and a really a bit of a nit, you have 4WD, not AWD. The V8 models with AWD have both axles engaged all the time through a viscous coupling and no way to disable that or select a low-range. That system does not allow the front and rear driveshafts to be "locked" so it does not provide quite the same traction available in the Control-Trac 4WD setup.
In the '97 and later versions of Control Trac, when you select either 4WD-Hi or 4WD-Lo the transfer case clutch pack is engaged continuously to lock the front and rear drive shafts together. This should only be used in poor traction conditions or going straight ahead as when the truck turns, the rear wheels go a shorter distance than the front and since the axles are locked together, something has to give! Either the wheels drag on the ground or something breaks or pops in the drive train. Shouldn't be trying that! In
4WD-Auto, the clutch pack in the transfer case is periodically pulsed to close, allowing drive line bind-up to be quickly relieved, and that engagement time is regulated by the GEM looking at the relieve speeds of the front and rear drive shafts. If the rear is going faster than the front, for example, it must be slipping so increase the clutch engagement time in 10% increments until the speeds match or the front is going faster than the rear.
The flashing lights mean "something" is wrong in the automatic system (usually a bad speed sensor or electrical connection, worst case a bad GEM or clutch pack), or low range is not getting engaged (bad limit switch or motor or just stuck). In the failure mode, the 4WD-Auto reverts to 2WD, only, but I believe you still engage and lock the clutch pack in the other positions. Sounds like you may have a problem with the Auto system (which is designed to handle rain and wet streets and such), but the rest may be OK if you are getting powered rotation of the front wheels. Check the connectors to the sensors and clean them, and try cleaning the gear (tone wheel?) inside as some have reported that fine shavings and crud can mess the sensors up. Next step would be to replace the sensors. Good luck!
I had this same symptom last year, I cleaned the metal sludge off of the sensors and it was OK for a couple of weeks. When the lights flashed again I re-cleaned the sensors AND changed the fluid. Been fine ever since. The fluid is easy to drain but you need a turkey baster, patience, and rolled up sleeves to refill it.
When you say you cleaned the metal sludge off the sensors, could you explain this to me. I have been looking for a book on how to repplace the sensors but cannot find anything local to purchase. Did you remove the sensors to clean them if so how did you do this. Is this hard to do? I am mechanically inclined. But I am just afraid to tackle this without prior knowledge. I don't want to open the proverbeal can o worms. Will there be leakage in changing the sensors? Do I need anything special? The sensors cost 28 for one and 17 for the other, I am hoping that this is all it is and the GEM and the shift motor is still good. Like I said before the front wheels spin when the rear lose traction so I figure the TX case is fine, I just don't hear anything to tell me that the shift motor is trying to do the job.
I can remember when my 68 dodge charger tranny went and all it cost was 350 for another one and the fix was quick n easy.... Now just to figure out what is wrong you need 1000 scan tools that give you a code that tells you whats wrong. I know its much better now but whew that difficulties for the average JOE are tremendous.
Regarding the shift motor, it is only used to shift in and out of 4WD-Low in the later versions of Control-Trac. If yours goes in and out of low range without problems, you can eliminate that as a possible problem. Other 4WD functions are done by changing the way the electromagnetic clutch pack is engaged in the transfer case. Also, the GEM controls a number of other functions such as wipers, door locks, and the interior lights. If there are no other symptoms besides the 4WD lights flashing, it is unlikely that the GEM has a problem. Usually the problem is related to the Hall-effect speed sensors in some way, from what I've seen. Good luck.
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