wish4hemi

I wonder if the RWAL module under hood is "calibrated" for drums in the way it modulates fluid to the rear when necessary. I might also wonder if the height sensing proportioning valve typical on drum-equipped 2500 8,800 GVW trucks would need to be removed with rear discs. It looks like the master cylinders between drum and disc trucks are different as well according to the parts books. Raybestos lists MC390426 for the 1999 (rear drum, 1.250" bore) and MC390732 for the 2002 (rear disc, 1.313" bore).

Were rear disc brakes on the 2001.5 and 2002 trucks only available with all-wheel anti-lock brakes? Or were there rear disc trucks made with rear wheel anti-lock (RWAL) only? I'm wondering how folks handle the drum to disc axle swap in regards to ABS as it seems like most of the rear disc trucks I've seen have all-wheel anti-lock. Is it prudent to run rear discs with rear wheel anti-lock only? This situation might exist if putting a rear disc axle in something like a 1999 truck with RWAL rear drums.

It's interesting that the Edge Juice with Attitude has a wire tap a little different than that of the Quadzilla Adrenaline. The Quad says it only uses the wire tap at Level 4 and above if I'm reading correctly. Edge states that the wire tap is used in all Juice with Attitude levels. A reply from their sales team when I asked about the wire tap function on their box: The VP44 tap will come into play in all 5 stages. It is demanding less in levels 1-2 than in levels 3-5 but it does increase fuel demand to create power.

I have another data point to add here for whatever it's worth. On a 7-hour trip through Missouri and Arkansas with an 8,500 lbs camper on, averages were ambient 75*F, engine coolant 195*F, NV4500 190*F, fuel temp 130*F. This is on Level 1 on the Edge JwA, stock Carter in-tank fuel module with stock return into the basket. The supply line is Evil Energy 3/8" braided hose all the way. Fuel pressure is a steady 18 psi.

@Great work! Fuse 16 in the junction block is the main thing that keeps the solenoid unlatched after the doors have closed and the 30-minute timer has expired. Since you have four wires to the driver's seat, your truck matches the service manual. "The driver seat belt switch is normally closed, providing a battery voltage signal to the instrument cluster when the ignition switch is in the On or Start positions." Section 8U-2. However, I do not believe this to be a problem with the seat belt switch in the retractor. It sounds to me like the SCTM is not getting the F13 18DB RUN-ACC feed from Fuse 16 in the junction block. Or maybe the power is being supplied but the SCTM is damaged internally and not taking that power signal correctly. Section 8W-67-2 An easy way to test this is to turn the truck off, leave the windows down, and walk away for 30 minutes. When you come back, leave the doors closed and reach in the window to tug on the driver's side belt. It should be locked. With the doors still closed, reach in the window and turn the ignition on. If that unlocks the belt, then Fuse 16 and the associated F13 circuit are working properly and the issue is elsewhere. If the belt is still locked with the doors having never been opened and the key is on, then the SCTM is not getting a RUN-ACC voltage.

“No you shouldn’t,” I think is the more appropriate verbiage lol. Once the current pump does die electrically, I think I’ll give the PSG swap a try and drag along the fuel solenoid, timing solenoid, fuel temp sensor, and tach sensor. The spare pump has a stuck timing piston and is mechanically defunct anyway. I wonder how much of the calibration is to make up for solenoid manufacturing differences and how much is related to the tolerances in the machining of pump internals. No matter; I’ll run the current 1688’d pump until it gives up the ghost either way. Many thanks for the input.

I do have a spare VP44 that should have good electronics. Maybe I’ll try swapping out just the PSG.

If it stops working after a half hour, then I think that means the SCTM doesn’t have power. If it unlocks when you get in the truck, then the door switch portion is working. Just not the ignition feed portion. The light comes on because the lock solenoid engages. I’ve not heard of that particular situation before. Out of curiosity, does your driver’s side seat have three wires going to it (no dark blue/white) or four (with dark blue/white)? There are 3 setups as far as I can tell (from earliest to latest): one where the retractor feeds a power signal to the dash, one where the retractor feeds a ground signal, and then the later one (post 98.5/99) where the buckle feeds a ground signal.

I know this is an older thread, but I've been doing some probing on this 98.5/99 seat belt function, specifically the buckle sensing switch which is actually part of the retractor. It seems to be a very strange little circuit and the switch that helps drive the light in the dash is not a simple on/off of the bulb. There seems to be some logic involved. My truck ('99) also has a three-wire plug going to the driver's seat. I've never found this plug to be shown in either of my 98 or 99 manuals, so the operation has always confused me. My three-wire plug going from the SCTM to the driver's front seat retractor has these wires: Orange, black tracer = power to the latch solenoid (it is locked when the power is off) Black, green tracer = ground to the latch solenoid Green, red tracer = this is the sense wire that tells the cluster if the belt is buckled or not (actually if it's retracted or not) The green/red wire is the strange one. On the cluster side of this wire (going from the cluster to the retractor), it shows 5v when the key is on. On the retractor side of this wire (going from the retractor to the cluster), it measures as an open circuit to ground when pulled out (belt buckled) and a 150-ohm resistance to ground when retracted (belt unbuckled). Also, that 150-ohm resistance is only present when the key is on and the latch solenoid is unlocked. If the key is off, the 150-ohm resistance goes to an open circuit. Basically, the cluster seems to send a 5v signal to the retractor which then shorts it to ground through a 150-ohm resistance when the belt is unbuckled. It's almost like the retractor is being used as a pull-down resistor, although that's a pretty low resistance for a pull-down application. I was going to connect the green/red wire straight to ground, but it looks like it would be a dead short of the 5v signal from the cluster. If my probing is correct, it seems very strange and matches absolutely none of the factory service manual literature.

This thread is the reason I joined the forum and "Great work!" is an appropriate handle for the OP. The possibilities are a joy to ponder given that this control along with something like a Holley digital dash and some basic wiring could eliminate the PSG, ECM, PCM, and factory cluster (a bunch of expensive components in the event that they do fail). Thank you for the time and the updates.

I'm trying a fusible link for this application. The downfall I can see is that I'll need a new cable if something goes awry. However, a component failure that bad is going to necessitate a trip to the parts store anyway. I like the fusible link because it's a clean install with no fuse to mount. One crimp and it's done. https://ceautoelectricsupply.com/product/fusible-links/

I'm also interested in this topic as I'm struggling to pull intelligent freeze frame data for a 1688 code. The OBDII plug-in I'm using defaults itself to "AUTO, ISO 9141-2" protocol which does allow me to read and clear the DTC. "SAE J1939 (CAN 29/250)" is also an option on this scanner. As pointed out above, there are several different communication standards which make it difficult to discern which information is coming from where and in what language. I wonder if AutoEnginuity would be any help if you contacted them directly? The freeze frames themselves look very strange. I see a -58F coolant temp, 193 RPM engine speed, 7,710 RPM engine speed, 150 MPH vehicle speed, etc. Are those because of unhooked components or because the AutoEnginuity tool is not doing a good job of pulling and putting together information? Maybe they could answer that.

I’m getting a recurring P1688 controller failure on my VP44. However, it’s easily cleared and the truck runs just fine. Could it just be the PSG is slow to boot up? Codes: 1688, 1693 companion Code reading/clearing method: Edge JwA Two scenarios 1. Turn the key on, 1688 is active, clear it, then start the truck without ever turning the key off. CEL never reappears as long as the truck is kept running. Idle is 800 RPM, idle load is 5% with new RV275s from DAP. The 1688 will never come back until the truck is turned off and back on. Runs great. 2. Turn the key on, 1688 is active, do not clear it, start the truck, leave the CEL on. Idle is sporadic from 860 to 1,000 RPM, engine load always shows 0% at idle. Truck can still be driven but acts very strange at idle while that 1688 is there. At this point, I’m just clearing the code before I drive it each day and have had no issues. Sometimes when I shut it off (like a fuel stop) then turn it back on, the code does not reappear. But 90% of the time it does come back after a key power cycle. It does not seem to be time sensitive as I’ve had it stay away for both 5 minute and 5 hour shutdowns. 2002 Dodge Ram 2500 Edge Juice w/ Attitude CTS, Cummins reman ECM (been installed for years), reman VP44 (been installed for years), factory PCM, 197,000 miles, good lift pump pressure of 20 psi (in-tank Carter), W-T mod is done, alternator charge wire goes straight to the passenger battery via fusible link, batteries are new, APPS is 0% at idle Another reference thread with similar issues?

Might the guy in Washington be Long Range Gear? I ran across them as well. Thanks for the input.

Any other input on this old thread other than Superstick and High Impact? Looking for something closer to me in the Illinois/Indiana/Missouri region.