Thread: 4BD1 Alternator

Have a strange problem with my latest aquisition(1988 land rover isuzu "110" ute) - the battery warning light won't go out even when i remove the wire from back of the alternator and only putting out 12V at battery-alt seems to be wired up correctly. The other strange thing is the fuel gauge reads backwards! I doubt it's related as probably something to do with different sender unit? Its the original hitachi LR170-401 alt.

Originally Posted by mattmac

Have a strange problem with my latest aquisition(1988 land rover isuzu "110" ute) - the battery warning light won't go out even when i remove the wire from back of the alternator and only putting out 12V at battery-alt seems to be wired up correctly. The other strange thing is the fuel gauge reads backwards! I doubt it's related as probably something to do with different sender unit? Its the original hitachi LR170-401 alt.

First thing I'd check would be that you have good earth straps between engine/trans and the chassis. If they look at all dodgy then just replace them. Fit one across the LH engine mount, and another from transfer case to chassis.
All sorts of weird crap happens when you've got bad earths.

Steve

Originally Posted by mattmac

Have a strange problem with my latest aquisition(1988 land rover isuzu "110" ute) - the battery warning light won't go out even when i remove the wire from back of the alternator and only putting out 12V at battery-alt seems to be wired up correctly. The other strange thing is the fuel gauge reads backwards! I doubt it's related as probably something to do with different sender unit? Its the original hitachi LR170-401 alt.

Matt, I am presuming that is a civvy 110 you are talking about. If so, that alternator was never factory fitted to it, originally they had the 40a one - that number you quoted is the Hitachi 70A model which is only found on army 110's and Isuzu 12V small trucks with the 4BD1T factory fitted. If the light is on and you are only getting 12V at the battery you can safely assume it is NOT charging. You need to get an auto leccy to look at it if all the wiring install looks ok. The fuel gauge problem would be unrelated and most likely earthing or sender problems.

Matt,
If the connector on your alternator is the one shown below you can do a bit of diagnostics. The L terminal is the output of the diode bridge in the alternator and should have volts on it when the engine is running - it should be a green wire. If you disconnect this from the alternator and connect it to 12V the alternator light should go out. If it does go out then the light circuit is working ok and it's more likely that the alternator is at fault.

The S connection is the Sense line coming back from the battery and should have battery volts on it.

The IG line should have battery volts on it when the ignition switch is turned on.

Good luck
Pete

thanks guys for advice -will check earth straps and wiring test.

local auto-elec diagnosis - alternator stuffed. looks like i better check flea-bay for a replacement unless anyone knows a place i can get a reasonably priced replacement.

Originally Posted by mattmac

local auto-elec diagnosis - alternator stuffed. looks like i better check flea-bay for a replacement unless anyone knows a place i can get a reasonably priced replacement.

There are a lot of similar alternators available. E.g. nissan patrol or holden rodeo both fit i have heard.
When the local auto elec buggered my hitachi 70a they sold me a very similar one for $170.
It only has 2 pins instead of 3 and i had to modify and rotate the vac pump fittings but apart from that was the same. It didn't have a part number so i can't tell you what it is from.