Possible Help With Default Code 9 2

[awtfit]

Little help hopefully, lol. Have a 2001 rd688, been in it since 2005, last year or so the lighting bolt lights up and shut down light comes on. Started with a lose in power as driving then would pick back up, speed meter stopping, yeah crazy. Rolled her in the local mack put in a new pedal, and new vecu updated version. Run alot better but I be dam the light still comes on and once in a while cuts off for a split second, more like a nose dive and picks back up. Here lately completely stalls out, will crank and run for about 30 seconds and shut down. May or may not stay running. Some days no problems at all, others cost me out the ying yang cause it decides its tired i guess. Light blinks code 9 2. All connections, batteries, etc were checked. Mack built it, If they don't know, I sure don't, maybe someone here does. Usally the lighting bolt lights up may or may not stay on but if it does then the speed meter quits, from there the shut down light comes on, from that sometime complete power shuts off, or the lights go off and back to normal. Honestly what good is it if ya scared to leave the yard in it. Thanks William.

[Mackpro]

Little help hopefully, lol. Have a 2001 rd688, been in it since 2005, last year or so the lighting bolt lights up and shut down light comes on. Started with a lose in power as driving then would pick back up, speed meter stopping, yeah crazy. Rolled her in the local mack put in a new pedal, and new vecu updated version. Run alot better but I be dam the light still comes on and once in a while cuts off for a split second, more like a nose dive and picks back up. Here lately completely stalls out, will crank and run for about 30 seconds and shut down. May or may not stay running. Some days no problems at all, others cost me out the ying yang cause it decides its tired i guess. Light blinks code 9 2. All connections, batteries, etc were checked. Mack built it, If they don't know, I sure don't, maybe someone here does. Usally the lighting bolt lights up may or may not stay on but if it does then the speed meter quits, from there the shut down light comes on, from that sometime complete power shuts off, or the lights go off and back to normal. Honestly what good is it if ya scared to leave the yard in it. Thanks William.

9-2 code is low voltage to either the engine ECM or the vechicle ECM. Start from the batteries and start checking every cable and connection, Check the block to frame grounds, look at the ground wires on the side of the block under the starter, check the ground breaker (black box ) on the driver side of the firewall. There is a service bulletin on the 9-2 code that tell everything to check, I'll see if I can find it. Seen a few starters short out inside and cause this. Had alot of RD's that had the VECU mounted with the connector/ plug-in end facing up and water would drip into the VECU and short it out and turn the pins green.

[awtfit]

Thank u mackpro68, I have been all over the net looking for the manual and had no luck, I only found the code sheets. On the Mack website that year truck is not listed under service manual, so what ever you have would be great. The vecu in the truck is new and up right, all wires checked many many times, batts 9 months old, amps hold at 14-15 never missing a beat, silinode new, starter hits off everytime, pedal new. Its got me lost, Any and all ideas would be great. Thank you, William

[MountainMech]

First of all Hi to Ya`All ,i went through all the post`s that sounded like it may pertain to my problem and found this one to be a close match, well I am dealing with a 2001 rd688s with the e7 350 the truck will on a test drive (that is all its good for right now )when i take it on a slight grade the check engine light goes on,the speed o quits and the truck will only operate at the very low step of the foot switch, a "Limp Home Mode " feel to it like some passenger cars will do . I have tested the bats each with a carbon pile tester that can handle the 1000 amp bats, cleaned all cables ,grounds at every point IE frame, engine,starter ect.ect. i had a new speed o sensor so swapped it out,checked not all but allot of harness connections that i felt could cause problems , i did find engine oil in the top connector of the ECM plus the fasteners at the bottom of the ECM were both broke (no telling how long its been banging hard as this truck sees allot of rough dirt roads, i removed the ECM opened it up found no oil inside , cleaned everything up mounted it back solid. I had a new starter from Mack as a back up and after hearing from others in the past abut internal shorts causing probs went ahead and swapped it,tested the ignition switch while driving checking voltage at all hot sides during the fault and all stays hot, i checked all power relays and trip fuses and all are ok , now the code i have is 4.2 this is i believe "Fan Clutch Output " OK ,the fan clutch works great engine does not get overheated (been 101 here lately)Well i have tested so much and all the while doing as i described above i would test drive the truck each step of the way ,and all most without exceptions the truck would at the slight grade on dirt ,no more bumpy that the asphalt i drove on to get to my test spot the thing would drop to the low end of the foot switch ,and the speed o would go off .Now if i creep to level ground set the brake and shut it down and turn the key the correct lights come on then off and she will start and be fine unless i continue uphill ,sometimes down as well but rare.Ok i am long wended but just wanted to give allot of info as possible, or maybe just venting the frustration lol .Well i will take all the advice you have and will greatly appreciate the help ,until then i will enjoy reading the posts about anything that sounds interesting to learn about . Thanks Again

Randy.

Edited July 22, 2012 by MountainMech

[Frmconcrete09]

My oh my . Wish I had the answer , but I'm still young and have never experienced your problems with our trucks , keep us updated if you can .. Sounds like a mess ...good luck

[MountainMech]

Thanks Big Dog .I will let you know this coming week ,and by the way after reading my own post over i noticed i had left out that the ABS light is on as well,i found that the rear left sensor cable is ripped , the driver never mentioned that the light was on ! well i ordered a new one from Denver Mack and it should be in UPS by tomorrow.I will keep ya posted KEEP ON TRUCK-EN .

Randy.

[alcoon61]

bad speedometer pickup maybe? My speedo pickup went bad and would cause it to cut the ecm back.

[staxx]

There is sevral power relays to the left of your fuse panel in glove box sometimes they get hot and start to stick try replacing one at a time or check and make sure where wires go in they are not melted wornout key switch will do this also and shorted altinator possability try loosening belt up and make sure bearing seems ok spins free no excessive noise.

[staxx]

Fuses CB-1 and CB-7 control power to vecu that is causing this code may try replacing or swapping with known good relays also ther is a ground lug post on left side dash behind speedometer tach panel make sure all wiresare tight and clean. There is alot more to this code sometimes but this would be a good place to start.

[chunkybunky]

Had a similar problem. 2001 R model E -7 460. Speedometer stopped working, engine power loss, shut down warning. Turned out it was the plug on the ecm behind the steel panel near the passengers feet. I had just moved everything to clean the a/c- heater core. I just cleaned the connections and all was good.

[rsb502]

Had a similar problem. 2001 R model E -7 460. Speedometer stopped working, engine power loss, shut down warning. Turned out it was the plug on the ecm behind the steel panel near the passengers feet. I had just moved everything to clean the a/c- heater core. I just cleaned the connections and all was good.

That is actually something I have done to two 2000 RD's, went thru same things on one then found some corrosion on the connector at the ecm on pass side cleaned it and it fixed the issue when the next truck did the same thing I went straight there and never had another issue.

[Mackpro]

9-2 code is one or both of the ECM's loseing voltage. Check the black box ground breaker and aux starter solinoid mounted on the firewall ( on driver side of engine compartment) . Check all power and ground connections. The grounding bolt under the starter into the engine block. There is a Mack Service Bulletin on this but I can find it now. Check and see if your cab ECM (VECU) is facing up, ( connectors up) if so flip it over and clean connections. The R series cabs were bad about leaking water right on to the VECU.

[Mackpro]

NUMBER: SB221032

DATE: 12/04/03

MODEL: ALL

TITLE: 9-2 FAULT CODE DIAGNOSTICS AND REPAIR PROCEDURES

<a name="s01">9-2 Fault Code Diagnostics and Repair Procedures

(Not applicable to Mack Trucks Australia)

(Supersedes bulletin SB-221-032 dated 3/20/03)

A 9-2 fault code "Power reset without Key Switch" (Failure Mode Identifier [FMI] 4, Parameter Identifier [PID] S254 and Message Identification [MID] 128/142), will set with a MID 142 if the Vehicle Electronic Control Unit (VECU) senses a loss of battery without the key switch being turned off. A 9-2 fault code will set with a MID 128 if the Engine Electronic Control Unit (EECU) senses a loss of switched power without the key switch being turned off. Fault code 9-2 generally indicates a loss of power or ground connection to the VECU or EECU. Complete electronic diagnostic procedures for troubleshooting a 9-2 fault code are outlined in the V-MAC® III Service Manual, 8-211 (dated October 2001 or later). In addition to the diagnostic procedures outlined in the V-MAC® III service manual, when troubleshooting the cause of a 9-2 fault code, the investigation should include the following:

The following procedures cover all chassis equipped with MACK engines and CL and CV model chassis equipped with Cummins engines.

To avoid a repeat failure, do not stop performing the procedures outlined in this bulletin at the point where it appears that the problem may have been corrected. All steps (steps 1 through 8), plus the voltage drop tests, must be performed to ensure that the cause of the 9-2 fault code has been repaired.

1. 
   Inspect the batteries.
   
   1. 
      
   2. 
      Load test each battery.
      
   3. 
      Check tightness of each battery connection. Clean and tighten as necessary.
      
   4. 
      If the vehicle is equipped with a battery disconnect switch, check the connections for corrosion and tightness. Clean and tighten as necessary.
      
   5. 
      Inspect the battery cable connections at the starter motor.
      
      1. 
         Before proceeding, disconnect the negative battery cables from the battery.
         
      2. 
         Remove the positive and negative battery cables from the starter motor. Note the tightness of the cable connections while they are being removed.
         
      3. 
         Note any corrosion on the cable ends, then clean both sides of the cable terminal.
         
      4. 
         Reinstall the battery cables and tighten the retaining nuts to 270 lb-in (31 N•m).
         

[*]

Inspect the left-side engine ground.

1. 
   Remove the bolt that secures the ground cable to the engine block (note the tightness of the ground bolt prior to removal). After removing the ground bolt, discard the star washer.
   
2. 
   Clean the ring terminals of all the ground wires, and also clean the ground bolt boss on the side of the engine block.
   
3. 
   Measure the length of the ground bolt, then measure the depth of the bolt hole in the engine block. Compare the measurements to be sure the bolt will not bottom in the bolt hole when tightened.
   
4. 
   Install the ground wire ring terminals onto the ground bolt, then install the bolt into the bolt hole in the engine block. Fan the ring terminals around the ground bolt so that the wire lugs are not on top of each other. Tighten the ground bolt to 120 lb-ft (163 N•m).
   

[*]

Inspect the left-side frame ground.

1. 
   Remove the bolt that secures the ground cables and wires to the left-side frame rail (note the tightness of the bolt prior to removal). After removing the bolt, discard the star washer (if equipped).
   
2. 
   Inspect the bolt and the wire ring terminals for signs of arcing or corrosion.
   
3. 
   Clean both sides of the ring terminals, making sure to remove all traces of the heat shrink sealant that may have oozed out during the heat sealing process.
   
4. 
   Clean around the ground bolt hole on both sides of the frame rail.
   
5. 
   Install the ground bolt, ground cable and wires, flat washer and nut. Fan the ring terminals around the ground bolt so that the wire lugs are not on top of each other. Tighten the nut to 37.5 lb-ft (51 N•m).
   DO NOT use a star washer.
   
6. 
   Spray paint the area of the frame rail around the ground bolt to prevent rust from forming.
   

[*]

Inspect the ground circuit breaker.

1. 
   Remove the retaining nuts that secure the cables to the terminals of the ground circuit breaker (note the tightness of the nuts prior to removal).
   
2. 
   Discard the nuts with the captured star washers.
   
3. 
   Clean both sides of the ring terminals, being sure to remove all traces of heat shrink sealant that may have oozed out during the heat sealing process.
   
4. 
   Install the wire ring terminals onto the terminal stud on the ground circuit breaker. Install a new nylock nut (part No. 21AX938) onto the terminal. Fan the ring terminals around the terminal stud so that the wire lugs are not on top of each other. Tighten the nut to 65 lb-in (6.16 N•m).
   

[*]

Inspect the left-hand side dashboard ground wire.

1. 
   Remove the instrument cluster and note the tightness of the ground bolt.
   
2. 
   Remove the ground bolt, discard the star washer and clean all the ring terminals.
   
3. 
   Sand or scrape to remove the paint from around the ground bolt hole.
   
4. 
   Install a flat washer over the ground bolt, then insert the bolt through the cross bar from the front side. Install another flat washer and secure with a prevailing torque nut.
   
5. 
   Install a flat washer over the bolt, then install the ground wire ring terminals, a flat washer and secure with a prevailing torque nut. Tighten the nut to 108 lb-in (12 N•m).
   

[*]

Inspect the right-hand side dashboard ground.

1. 
   Remove the "D" panel from the dashboard, then check the tightness of the ground bolt.
   
2. 
   Remove the ground bolt, discard the star washer and clean all the ring terminals.
   
3. 
   Sand or scrape to remove the paint from around the ground bolt hole.
   
4. 
   Install a flat washer over the ground bolt, then insert the bolt through the cross bar from the front side. Install another flat washer and secure with a prevailing torque nut.
   
5. 
   Install a flat washer over the bolt, then install the ground wire ring terminals, a flat washer and secure with a prevailing torque nut. Tighten the nut to 108 lb-in (12 N•m).
   

[*]

If the 9-2 code is logged in the VECU, proceed as follows:

1. 
   Remove fuse or circuit breaker No. 16 from the electrical equipment panel.
   
2. 
   Insert the purple male test lead adapter included in the Kent-Moore V-MAC® Test Lead Adapter Kit (tool No. J 38581) into the female terminal to check the tightness of the terminal.
   
3. 
   If the drag felt on the test lead is not sufficient, replace the female terminal end (part No. 925AM173).
   
4. 
   Remove power relay Nos. 1 and 2 from the electrical equipment panel.
   
5. 
   Check the terminal blades of the relays for deep scratches which indicated good contact between the female terminals and the male terminal blades of the relays.
   
6. 
   If deep scratches are not present, inspect the female terminals for damage or spreading. Replace the female terminals as required (part Nos. 2967-2807554 [Amp Industries part No. 280755-4] and 2967-422811 [Amp Industries part No. 42281-1]).
   Although the power relays may seem tight when being removed from the electrical equipment panel, this does not indicate sufficient contact between the male and female terminals. The only way of determining sufficient contact is by looking for deep scratches on the male terminals.
   

[*]

If the 9-2 code is logged in the EECU, proceed as follows:

1. 
   Remove fuse or circuit breaker No. 40 from the Engine Power Distribution Module (EPDM).
   
2. 
   Insert the purple male test lead adapter included in the Kent-Moore V-MAC® Test Lead Adapter Kit (tool No. J 38581) into the female terminal to check tightness of the terminal.
   
3. 
   If the drag felt on the test lead is not sufficient, replace the female terminal end (part No. 6031-12110844).
   
4. 
   Disconnect connector "B" from the EPDM.
   
5. 
   Inspect the connector terminals for corrosion and other damage, and check to make sure that each terminal is fully seated and locked in the connector body.
   
6. 
   Disconnect the engine-to-transmission transition connector.
   
7. 
   Inspect the terminals for corrosion and other damage, and check to make sure that each terminal is fully seated and locked in the connector bodies.
   

Testing Voltage Drop

Measuring voltage drop across a cable or a cable connection is useful in determining the integrity of the circuit. Cables or connectors should have no measurable, or only a fractional voltage drop. For a wire, cable or connector, voltage drop should be 0.1 volt or less, and for an insulated or ground circuit, voltage drop should be 0.5 volt or less. Voltage drop measurements greater than 0.1 volt for a cable or connector indicate the presence of high resistance that could be caused by a loose connection, dirt or corrosion. When diagnosing a 9-2 fault code, the following voltage drop tests should be performed, and the information gathered from these tests should be recorded on the "Voltage Drop Test/Battery Load Test Results" form included at the end of this service bulletin. The completed form can then be faxed to the Mack Trucks Electronic Service Engineering Department for analysis.

Voltage Drop Test Procedures

Voltage drop is measured by placing a digital multimeter (volt-ohm meter) in parallel with the component (wire, connection, etc.) as follows:

1. 
   Set the multimeter to the VDC function.
   
2. 
   Turn the vehicle ignition switch to the ON position.
   Long jumper wires with alligator clips on both ends may be used to facilitate performing the following tests.
   
3. 
   Measure voltage drop on the positive side of the battery by placing the positive meter lead on the positive battery post (terminal), then place the negative meter lead at the following test points:
   
   
   1. 
      Measure voltage drop on the negative side of the battery by placing the positive meter lead on the negative battery post (terminal), then place the negative meter lead at the following test points:
      
      1. 
         Battery negative post to battery negative cable end
         
      2. 
         Battery negative post to starter ground terminal
         
      3. 
         Battery negative post to frame ground
         
      4. 
         Battery negative post to master ground circuit breaker
         
      5. 
         Battery negative post to left-hand side dashboard ground terminal
         
      6. 
         Battery negative post to right-hand dashboard ground terminal
         
      7. 
         Battery negative post to alternator ground (G) terminal
         
      8. 
         Battery negative post to left-hand side engine ground connection
         

[*]

Record the voltage drop measurements obtained at the above locations in the form provided with this bulletin. If voltage drop measurements are higher than specified, clean the connectors, terminals, etc., as required and retest.

In addition to the above voltage drop tests, also perform an open circuit voltage test and load test of all the batteries. Include this information on the form provided with this bulletin.

For information concerning voltage drop tests, battery open circuit voltage tests and battery load tests, refer to the MACK Electrical Troubleshooting Manual, 8-212.

Battery positive post to battery positive cable end

Battery positive post to starter solenoid battery ( terminal

Battery positive post to starter relay battery ( terminal

Battery positive post to power relays 1, 2, 3 and 4

Battery positive post to alternator positive ( terminal

[mcratchet1]

i am having same problem with my 2006 mr688s (032711) i followed all the steps above and had no luck it was doing it once a month then once a week now 1 or 2 times a day its loses power like it was turned off but the truck never shuts off and the code is logging from vecu any other ideas? thanks!!

Edited August 14, 2019 by mcratchet1