RLHack66
New Member
- Joined
- October 1, 2011
- Messages
- 4
- Reaction score
- 0
- City, State
- Corona CA
- Year, Model & Trim Level
- 1998 Explorer XLT 4x4
So I have been searching and digging deep into the many threads on this site dealing with the 2nd Gen 4405 transfer case and issues with engagement of the 4 WD features. I have a 98 XLT, 4.0 SOHC with the "Auto/Hi/Lo" knob on the dash (i.e. live front axle). Our family car as well as our off-rad exploration vehicle. Have used in low to mid level difficulty dirt road and back country trails for 15 years with no issue. Exclusively have left in 4WD auto for 99.9% of the time over the years. In late March, I was on a trail in Death Valley and got the Explorer stuck up to the axles. Got it out after a few hours of effort. While stuck I tried to engage 4 Hi and 4 Lo. Dash light came on in both modes (including the 4Lo process of shifting to neutral and apply the brake). Didn't think too much about it since my first priority was to get unstuck. Once out and clear, I pondered the fact that the front wheels never turned when stuck, only one of the back wheels were spinning/losing traction (an open rear differential).
When I got back home, started searching and immediately came across gijoecam's Jan 2008 thread on diagnosing 4WD maladies. Following his procedure, lifting the front axle, engine on, knob set to 4WD-Hi, the front wheels turn fine and the front drive shaft does not lock. Checked all the fuses, all are good. No error codes (i.e. no flashing sequence of the "4 Hi" and "4 Lo" lights
So...with this as background, I am seeking some information on the signal/power that is sent to the magnetic coil/clutch on the 4405. Reading some of the threads on the "brown wire modification" I saw some specifications on the nominal current draw (5 amps I recall) for a specification on the BWM switch but no specifications on the voltage. I have measured the voltage on the brown wire about 6-inch upstream of the t-case; in 4WD-high, I measure 2.0 VDC, in 4WD-Auto, I measure 0.07 VDC (as described in other threads, I know in 4WD -auto there is a small voltage applied; I definitely measured something low but non-zero). Does this seem correct? My first guess would be that I should measure 12 VDC in 4WD-hi but then thinking a bit more, I realize that the signals coming from the GEM box and the electronic shift control module (both microprocessor based units that likely operate on relatively low voltages) may be something on the order of a 5 VDC signal or less. This is what I measure at the grey/red wire pin on the dash switch. So a 2 VDC, 5 amp service would imply 10 watts of power to engage the magnetic clutch. Seems plausible.
The fact that I am getting different non-zero voltage signals in the two modes (4WD-auto and 4WD-hi) and that I can envision the signals being on the order of what I measured suggest to me that my electronics (the GEM and Electronic Shift Control Module) are probably working correctly. Further, it suggests that my problem is in the transfer case (BUMMER!!)
Seeking the collective wisdom of the Explorer forum for:
1) Any input on the voltage signal I should see at the brown wire would be very much appreciated.
2) Any process for external diagnosis of the t-case. The case is quiet with no banging, grinding rattling or other bad sounds. Based upon the "4405 rebuild diary thread" my guess is the ball-ramp disks may have broken. Certainly the chain could have broken but the lack of noise suggests otherwise.
Thanks much
When I got back home, started searching and immediately came across gijoecam's Jan 2008 thread on diagnosing 4WD maladies. Following his procedure, lifting the front axle, engine on, knob set to 4WD-Hi, the front wheels turn fine and the front drive shaft does not lock. Checked all the fuses, all are good. No error codes (i.e. no flashing sequence of the "4 Hi" and "4 Lo" lights
So...with this as background, I am seeking some information on the signal/power that is sent to the magnetic coil/clutch on the 4405. Reading some of the threads on the "brown wire modification" I saw some specifications on the nominal current draw (5 amps I recall) for a specification on the BWM switch but no specifications on the voltage. I have measured the voltage on the brown wire about 6-inch upstream of the t-case; in 4WD-high, I measure 2.0 VDC, in 4WD-Auto, I measure 0.07 VDC (as described in other threads, I know in 4WD -auto there is a small voltage applied; I definitely measured something low but non-zero). Does this seem correct? My first guess would be that I should measure 12 VDC in 4WD-hi but then thinking a bit more, I realize that the signals coming from the GEM box and the electronic shift control module (both microprocessor based units that likely operate on relatively low voltages) may be something on the order of a 5 VDC signal or less. This is what I measure at the grey/red wire pin on the dash switch. So a 2 VDC, 5 amp service would imply 10 watts of power to engage the magnetic clutch. Seems plausible.
The fact that I am getting different non-zero voltage signals in the two modes (4WD-auto and 4WD-hi) and that I can envision the signals being on the order of what I measured suggest to me that my electronics (the GEM and Electronic Shift Control Module) are probably working correctly. Further, it suggests that my problem is in the transfer case (BUMMER!!)
Seeking the collective wisdom of the Explorer forum for:
1) Any input on the voltage signal I should see at the brown wire would be very much appreciated.
2) Any process for external diagnosis of the t-case. The case is quiet with no banging, grinding rattling or other bad sounds. Based upon the "4405 rebuild diary thread" my guess is the ball-ramp disks may have broken. Certainly the chain could have broken but the lack of noise suggests otherwise.
Thanks much
