Key on and no power to dash lights (horn doesn’t work either). Battery replaced, seat switch tested, main circuit breaker ok(power to both sides). Checked fuses. I have a wiring schematic. Help please
If you already have the schematic (provided it’s correct for the Serial Number) there isn’t much to suggest other than start from the battery tracing power until you reach a point where it disappears. At that point you have found your problem.
Pulled harnesses off all six relays in the engine bay. 12.5 volts on all red wires to machine ground on all six. Turned key switch on and voltage dropped to 2.7 volts on all six relays. Is that normal? Key switch off position brown and purple had 12.4 volts and in the on position brown and yellow had 2.7 volts as well…. Any ideas?
You have the advantage here in that you know what you are dealing with....... Machine Serial Number.? Cat Publication reference of the electrical schematic you are using.?
CAT00226P5FZ08268
Schematic for 226 5FZ5200-UP
That's weird. The schematics I see are for 5FZ1-5199, 5200-6699 & 6700-Up. Obviously the latter applies to your machine. Got a pulbication reference.? I suspect that you may not be working with a schematic that is appropriate to the Serial Number. It may not make any difference but who knows.?
Part number 203-1799, change 02 RENR4826-02 December 2008
That is a document originally published for machines 5FZ5200-Up that was later republished for a specific range of 5FZ5200-6699. Published in 2010, RENR4823 covers machines 5FZ6700-Up. Keep an eye on your message inbox. I'll send you a copy.
Thank you!!
Post #3 above you state that the power drops off greatly to the harnesses with the relays disconnected. That indicates that there is a bad connection feeding all of it. You need to stab the battery positive post center with the red lead and then stab the Starter Positive post on the solenoid with the black test lead while someone turns and holds the key in the start position. If your multimeter is reading more than 0.4-0.5 volts your cable has grenaded internally somewhere. Could also test from Starter solenoid positive Post with the red test lead and stab the relay large red feed wire with the negative test lead while someone holds the key in the start position to see how much loss to the relays. The relays should all be plugged in to do these tests. Test this out and let us know what kind of numbers you got. Simon C
Battery post to starter solenoid post key on: no voltage. Key in start: no voltage. Starter solenoid post to red wire to start relay with key on : no voltage. Key in start: no voltage. Battery positive post to red meter lead to machine ground with key in off position 12.7 volts. Key in on position 2.6 volts????
This makes it look like you have 2 good positive cables. How about stab the starter on the side on clean metal with the black lead and stab the red lead on the center of the NEGATIVE post of battery and have someone hold in start position for 5 seconds. What does meter record? Stab no paint bare steel frame with back test lead and Stab NEGATIVE post again with the red test lead while someone is holding the key in the start position. What does meter record? Please post results as the problem is quickly narrowing down. Did you check your fuses with the multimeter or a test light as I have seen burnt fuses that rewelded themselves and would not run a test light, but showed good with Multimeter as there was still a tiny path across the fuse. Simon C
Thought about 1 more test you could do to find out about the state of the cab grounding. Stab the cab inside close to the key switch on bare metal with the Red test lead and the black test lead to the center of the Negative post of the battery while someone turns the key on. What reading is on the meter. Trying to narrow down your power problem. Simon C
I will do these tests soon and let you know what I find. Between work and sub zero temps it’s been tough to get out and check more. I appreciate the help!
How about stab the starter on the side on clean metal with the black lead and stab the red lead on the center of the NEGATIVE post of battery and have someone hold in start position for 5 seconds. What does meter record? 10.6
Stab no paint bare steel frame with back test lead and Stab NEGATIVE post again with the red test lead while someone is holding the key in the start position. What does meter record? 10.3
Stab the cab inside close to the key switch on bare metal with the Red test lead and the black test lead to the center of the Negative post of the battery while someone turns the key on. What reading is on the meter. 10.7
This 10.6 volt loss of potential means you need to run a new cable from the engine block to the battery negative, or to the frame ground. It depends how your cables are routed. You definitely have a great loss on this cable or series of cables. Start with fixing the 10.3 volt loss frame to Battery negative cable first. Your Frame to Battery negative cable is done with a reading of 10.3 volts. Could be one end bad or burn't off inside, or so rusty no connection on one end. After fixing the frame to battery negative post cable, try a restart and if nothing works fix the engine block to either the frame or to the negative post. Depends on how configured. Let me know what happens. Simon C
Seem to recall from working on these machines, there is usually a Ground cable bolted up to the bottom of the starter and straight to the battery Negative. The have a lead connector that is hooked up to the battery negative that I know on a few occasions has burn off internally. I replaced one with copper lugs crimped on with pliers and heatshrink. Grote makes quality copper ends for 1/0 and 2/0 cables. I usually use fine strand welding cable. By any chance would your machine have a master disconnect switch tied into the negative cable. Maybe a picture of the battery box would really help. Just to let you know, many a time you will not be able to see a cable burnt off internally at the battery end or under some heatshrink. Simon C
You’re a damn genius!! Jumped the negative battery post with a 12ga wire to the where the negative cable attaches to starter bolt stud and dash power came on. Hooked a heavy duty jumper cable on negative post to ground and machine started. Pulled off negative cable and tested ohms at 2.2. Put battery post connector on vise (crimped) tested at .1 ohms. Reinstalled cable, started, and parked in HEATED shop to finish putting everything back together. New cable on order and drinking beer now!!! I sincerely appreciate all the help!!!
Ohms tests are okay to tell you if you are on the same cable, but can fool you with a no start yet pass an ohm test cause there is no current flowing through it. A voltage drop test as I told you to do will be much more accurate in diagnostics. Even with only 1 strand left in cable from one end to another , you will have a perfect ohms test. Nothing will run. Any more questions , fire away. Cheaper than a parts cannon. Simon C