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Peyton
New Member
3 Posts |
 Posted - 02/05/2016 : 10:14:26 AM
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Hi,
I'm new to this forum, I work in an auto repair shop and we work on the buses for several local schools. I have a 2006 Bluebird Vision with a C7 Cat giving me fits. The "wait to start" light is on constantly KOEO or engine running and the grid heater is never activated at cold start up. If I supply power and ground to the solenoid it activates and the heater works as it should, with the signal wires disconnected I have ground on one and 7.2 Volts on the other. If I understand correctly the ECM provides ground, but I cannot find where the Positive signal comes from or why I only have 7.2V, and with the negative wire hooked up if I supply 12V on the other terminal the electric brake booster runs (are these systems connected?) I have checked all fuses, breakers, ground studs, cannot see any wiring damage, Coolant temp sensor works correctly and Intake air temp sensor Ohms out the same, Batteries are good and no check engine light is on. Thank you in advance to anyone who has any insight on this problem! |
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bwest
Administrator
United States
3820 Posts |
Posted - 02/05/2016 : 12:06:15 PM
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| Go here http://service.blue-bird.com/WiringSchematics/ & you can put your body number in and get some information that way. I'm not sure if they will show the part you are looking at though. It might be a Cat schematic. I am trying to remember how mine was when I had that problem several years ago. I'll post if I get a handle on it. lol Someone else will probably have an idea and post here shortly. |
Bryan |
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Peyton
New Member
3 Posts |
Posted - 02/05/2016 : 12:34:36 PM
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| Thanks Bryan! I have gone through every wiring diagram available through Bluebird and unfortunately they didn't have the info I needed. I spoke with a guy that suggested unhooking the alternator exciter wire as it was tied into the same circuit and could keep the light on but it didn't solve my problem, I do however have the same .7 volts on that wire that I have on my Heater relay signal wire. My main issue is finding the power supply to that circuit to see if it's a supply issue or circuit issue. Normally I would open up the harness and trace it all the way but this school has no spare buses so this one has to be used everyday, and with the amount of wiring here I would need two days to do that! |
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aaronwilmoth80911
Top Member
538 Posts |
Posted - 02/05/2016 : 2:35:26 PM
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| Do you have access to CAT ET? If so, this may help. What is the prefix on the engine serial number? I'm thinking it should be a KAL or WAX. I have some info back at work, but unfortunately I didn't see your post in time, otherwise I would be able to give you some info right now. I'll try to give you some info on Monday. |
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Peyton
New Member
3 Posts |
Posted - 02/05/2016 : 3:18:05 PM
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| The engine serial is WAX05291, 210HP Acert built in '05. Sadly I don't have access to Cat ET, I don't have any type of HD diagnostic equipment at the moment, we are setup for light duty but I was a diesel mechanic prior to working here and I am slowly getting us setup for heavy duty. I'm looking into the OTC 3417 and the Blue Point Pocket IQ. With the small amount of work we do on HD I can't justify the cost of a better system (yet). |
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mickalobe
New Member
1 Posts |
Posted - 11/28/2018 : 1:56:10 PM
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I just had this exact same problem, I found the body computer had no output on a pink wire B2 pin 5 this powers the electric brake, the ignition relay , an ignition fuse panel under the dash also the intake heater!! 2 years later hope this helps someone
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Bluenozer
Top Member
Canada
644 Posts |
Posted - 12/03/2018 : 02:55:17 AM
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| the heater will come on if the intake temp. sensor reads cold even when driving the heater will cycle could be a bad intake temp. sensor |
OEM trained in wiring and all engine platforms for over 20 years
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Topic |
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Cat C7 Intake Heater Relay Signal and Ground
