Start failure-no crank-fixed it.

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Start failure-no crank-fixed it.

June 18, 2012, 05:01:33 pm

My 8.3 with 3060 trans is not responding to the key start or auxiliary start. The voltage is good, the selenoid under dash is working properly and when I apply 12V to the auxiliary start selenoid it cranks right up. Reading the wiring diagram I see that the coil circuit for the start selenoid passes through a NS switch. I'm thinking that's a neutral safety switch, does anyone know where this switch is located? Hopefully not in the trans wiring harness....

Problem traced to a substantial and obsolete Trekmate security system which has an ignition interlock.

Chuck

Re: Start failure-no crank-fixed it.

Reply #1 – June 19, 2012, 12:00:32 am

Chuck, I have documented our starting circuit in detail. Here is one view. The next posting will have another view.

   starter engage circuit from wiring diagram

   start battery cable connections
1   Start battery positive post
2      starter solenoid terminal
3      to boost solenoid terminal
4         isolator terminal
5         to 90 amp circuit breaker terminal (behind white bay wall panel)

   30 amp Allison circuit breaker (behind white bay wall panel)
6      input B69
7      output C6 red

   10 amp Allison circuit breaker #1 (right-dash panel)
8      input ATEC-ECM C6 red
9      output ATEC-ECM 136 white

   Allison transmission ECM (behind lower left driver seat side kick panel
10      inputs B2-136A & B11-136C - unswitched battery +
11      output A23-123 PU Violet - neutral-start output when trans in neutral (closes relay #1 coil)

   ignition switch
12      input 91 white from 15 amp circuit breaker #28 (located on front dash breaker panel start batt buss)
13      output 122 white start position to neutral safety relay common

   neutral safety bosch relay R1 (right side of front dash CB panel)
14      relay 86 coil from step#11 (trans neutral closes relay) 123 purple
15      relay 85 coil (battery negative connected to other coil terminal)
16      relay 30 common is from ignition switch start position 122 white step#13 (or from remote start button E23)
17      relay 87 N/O is E9 white to aux start solenoid coil (powered from ignition switch start) on isolator panel
        (aux start sol below closes when when trans in neutral & ign key in start position)
        (and aux start solenoid coil is powered from ignition key start position)

   auxilary start solenoid (located on inverter panel)
18      coil small wire from step#17 (battery positive closes relay)
19      input large side post from start battery positive step#4 B26 red
20      output large side post to starter solenoid coil B25 red

Re: Start failure-no crank-fixed it.

Reply #2 – June 19, 2012, 12:03:16 am

view #2 of starter circuits

   wire
circuit   code     description


START BATTERY
   B1 000   start battery POS post big cable goes to starter solenoid large terminal
   B5 000   start battery NEG post new very big cable bolted to motorhome frame [change to bolt to engine]

STARTER
   B5 000   big cable from battery to starter solenoid large terminal
   B14 2RD   big cable on start solenoid goes to rightmost isolator terminal

ISOLATOR
   B14 2RD   big cable from starter solenoid
   B15 2RD   large cable to 90-amp circuit breaker on bay wall panel
   B26 RD   wire to aux start solenoid on isolator panel aux start solenoid

BAY WALL PANEL BREAKER
   B15 2RD   large cable from isolator to leftmost 90-amp big round start battery circuit breaker's lower terminal
   B69   wire from 90-amp breaker to 30-amp ATEC circuit breaker on bay wall panel
   C6 RD   10-gauge wire from 30-amp ATEC breaker to front door panel

FRONT DOOR PANEL BREAKER
   C6 RD   wire from bay wall panel to leftmost 10-amp ATEC-ECM circuit breaker located on top-row
   136 WH   wire from 10-amp breaker to Allison ECM interface-plug RD# 136A & 136C, "unswitched batt +"

ALLISON ECM COMPUTER
      ECM computer is located behind carpeted side panel to the left of driver's left foot
   136 WH   wire from 10-amp breaker to both terminals RD# 136A & 136C, labeled "unswitched batt +"
   123 PU   wire from ECM terminal PU# 123, labeled "neutral safety", indicating transmission is in neutral, to neutral safety relay

FRONT DOOR PANEL RELAY
   123 PU   12-volt positive from Allison, when transmission is in neutral will close #86 coil on neutral safety relay
   green   ground wire completes #85 coil circuit on neutral safety relay located 2nd from bottom on right side of panel
   122 WH   ignition key momentary start position flows start battery current to neutral start relay #30 common terminal
   E9 WH   ignition key current flows from N/O #87 relay terminal to aux start solenoid located on isolator panel

ISOLATOR PANEL SOLENOID
      AUX START solenoid is leftmost of the two solenoids and is located in center of isolator panel above air cleaner
   E9 WH   ignition key current flows through neutral start relay to small coil terminal on the aux start solenoid, coil is internally grounded to case
   B26 RD   start battery current flows from isolator terminal through aux start solenoid when solenoid is closed (by ignition momentary start)
   B25 RD   when aux start solenoid is closed start battery current flow to starter solenoid coil to activate engine starter, coil is internally grounded

IGNITION RELAYS
      IGNITION DUAL-RELAYS are large cube-shaped and are mounted to lower center of front door panel
      REMOTE STOP RELAY is positioned lying loose in bottom center of front door panel
   103 WH   when ignition key is turned on, 103 WH flows start battery current through secure-switch to
        remote-stop relay #30 common terminal and through NORMALLY-CLOSED #87A terminal
   103A WH     to dual-ignition-solenoid coils to close ignition relays, which allows start battery current to flow to ALL ignition circuits

REAR ENGINE REMOTE START PANEL
   E21 WH   ignition circuit breaker #19 located in front door panel powers remote start system start & stop momentary push button switches
   E23 WH   pushing remote start switch powers ignition key start wire E22-WH to turn starter on (same as turning ignition key to start positon)
   E61 WH   pushing remote stop switch powers remote stop relay #86 coil, opening relay and turning 103A-WH power off to ignition dual-relays
   green   ground wire completes #85 coil circuit on remote stop relay
      when remote stop relay is powered, 103A-WH power from ignition key is disrupted, turning off ALL ignition circuits MOMENTARILY,
        which kills power to engine fuel shut-off solenoid, thus stopping engine
        letting up on remote stop switch allows ignition dual-relays to again close, as ignition key is still on

Re: Start failure-no crank-fixed it.

Reply #3 – June 19, 2012, 12:13:36 am

View #2 answers your question the NS switch is a neutral start relay on our coach. When we had a start problem, I put lights on the relay coil and points to observe a fast flow of current when the ignition key was turned to start position.

From the circuit description, you will see a dedicated circuit breaker behind the white bay breaker panel the flows start battery current directly to Allison through another breaker by the front door panel. I replaced both breakers to be sure they were not intermittent. Allison flows current to neutral start relay coil, to close relay points when ignition is on and transmission is in neutral. The ignition key start position flows current through close relay points to the aux start solenoid that you manually tripped to run starter.

Let us know if you need help with diagrams.

Re: Start failure-no crank-fixed it.

Reply #4 – June 19, 2012, 12:21:13 am

Chuck, let us know what you find on your coach.
The wiring diagram views, I put together for myself have not been shared before, so I don't know if others will find them useful.

Re: Start failure-no crank-fixed it.

Reply #5 – June 19, 2012, 10:01:15 am

Jeeze, and I think my lawn mower starter is overly complicated. Next thing you could do is pictures of everything

What were your symptoms when you were having start problems?

Re: Start failure-no crank-fixed it.

Reply #6 – June 19, 2012, 11:42:18 am

Barry, I have made notes on your information for possible future need. I would like to add the wiring diagrams you used if possible.
Thanks, Dick

Re: Start failure-no crank-fixed it.

Reply #7 – June 19, 2012, 05:27:17 pm

Wow! This is most impressive diagramming. I have to admit, I flat lucked into finding the problem with mine, it was an internal relay in the Trekmate security system. I'm going to ring that thing out one of these days, who knows what tricks it's capable of pulling. I thought it was non functional.

I wonder why there is any need for a neutral safety switch with the Allison automatic? It defaults to neutral when the engine shuts down anyway. Redundant safety I suppose.

Your fabulous and easy to understand description is bookmarked, printed, added to elec. drawings and Karma to you.

Re: Start failure-no crank-fixed it.

Reply #8 – June 27, 2012, 10:45:54 pm

Our starting problem was a hesitation after turning ignition key to start position.
After a short pause, which made us think it would not start, the engine would start.

The names of our wiring diagrams I used to trace our starter circuit:
B-2126 Automotive Wiring Diagram
A-5894 ATEC Interface Diagram
A-4752 Remote Start Wiring Diagram
B-2198 12V Wiring Diagram

Re: Start failure-no crank-fixed it.

Reply #9 – June 28, 2012, 11:43:27 am

Barry,
More karma from me. Love your imformative posts. Thank you for sharing your hard work.
Rick D.

Re: Start failure-no crank-fixed it.

Reply #10 – February 07, 2015, 10:06:10 pm

Quote from: Barry & Cindy – June 19, 2012, 12:00:32 am

I have documented our starting circuit in detail. Here is one view. The next posting will have another view.
starter engage circuit from wiring diagram

I have been wanting to do this for my 2003 U320 after reading Barry's post. It has been on my to do list. I did not realize how long it has been there. Got together with Barry in Yuma and got it done. I am a visual so picture is worth $$$

Re: Start failure-no crank-fixed it.

Reply #11 – February 07, 2015, 10:41:42 pm

Wow ! Great work.....

Re: Start failure-no crank-fixed it.

Reply #12 – February 08, 2015, 10:00:13 am

Wonderful! Thank you.

A benefit of owning a 2003 320 is that I get the benefit of Barry (and Michelle/Steve) sharing so much knowledge .

Again, thank you!

Re: Start failure-no crank-fixed it.

Reply #13 – February 08, 2015, 12:47:09 pm

Quote from: Barry & Cindy – June 27, 2012, 10:45:54 pm

Our starting problem was a hesitation after turning ignition key to start position.
After a short pause, which made us think it would not start, the engine would start.

The names of our wiring diagrams I used to trace our starter circuit:
B-2126 Automotive Wiring Diagram
A-5894 ATEC Interface Diagram
A-4752 Remote Start Wiring Diagram B-2198 12V Wiring Diagram

There has always been about a second and a half wait before the starter engages. Now, I turn the key to the run position, wait a couple of seconds and then engage the starter. As soon as the key is turned to the run position, the warning lights come on and the entry stairs retract. Exactly the same the last five years. Did make me wonder the first few times.

Pierce

Re: Start failure-no crank-fixed it.

Reply #14 – February 11, 2015, 01:57:27 pm

The Amazing Barrys. Thank you for sharing all your information with us.

Deb and Mike

Re: Start failure-no crank-fixed it.

Reply #15 – February 13, 2015, 09:10:23 pm

Now that our coach has been starting reliably on first crank, we decided a few cranks without start may be an good thing, as it could build some oil pressure before engine fires.

We now have a dash push button switch that prevents fuel solenoid opening while we crank a few times, before releasing push bottom to fire engine.

Re: Start failure-no crank-fixed it.

Reply #16 – February 14, 2015, 12:57:17 pm

Barry,

The delay button is an interesting idea. It is much like the starting procedure for the old WW-II radial aircraft (gasoline) engines. The procedure normally includes turning on an oil circulating pump before cranking. Then cranking the engine and counting a certain number of propeller blades going by before the ignition is turned on.

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Start failure-no crank-fixed it.

June 18, 2012, 05:01:33 pm

Re: Start failure-no crank-fixed it.

Reply #1 – June 19, 2012, 12:00:32 am

Re: Start failure-no crank-fixed it.

Reply #2 – June 19, 2012, 12:03:16 am

Re: Start failure-no crank-fixed it.

Reply #3 – June 19, 2012, 12:13:36 am

Re: Start failure-no crank-fixed it.

Reply #4 – June 19, 2012, 12:21:13 am

Re: Start failure-no crank-fixed it.

Reply #5 – June 19, 2012, 10:01:15 am

Re: Start failure-no crank-fixed it.

Reply #6 – June 19, 2012, 11:42:18 am

Re: Start failure-no crank-fixed it.

Reply #7 – June 19, 2012, 05:27:17 pm

Re: Start failure-no crank-fixed it.

Reply #8 – June 27, 2012, 10:45:54 pm

Re: Start failure-no crank-fixed it.

Reply #9 – June 28, 2012, 11:43:27 am

Re: Start failure-no crank-fixed it.

Reply #10 – February 07, 2015, 10:06:10 pm

Re: Start failure-no crank-fixed it.

Reply #11 – February 07, 2015, 10:41:42 pm

Re: Start failure-no crank-fixed it.

Reply #12 – February 08, 2015, 10:00:13 am

Re: Start failure-no crank-fixed it.

Reply #13 – February 08, 2015, 12:47:09 pm

Re: Start failure-no crank-fixed it.

Reply #14 – February 11, 2015, 01:57:27 pm

Re: Start failure-no crank-fixed it.

Reply #15 – February 13, 2015, 09:10:23 pm

Re: Start failure-no crank-fixed it.

Reply #16 – February 14, 2015, 12:57:17 pm

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