IMA light w/o code. What could it be?

[racer26]

Was driving down the highway, IMA light came on, accompanied by loss of IMA functionality.

Drove to a service facility (I was out of town, I would have gone to my own shop otherwise), and had them read the codes, they were gracious enough to do it for free. Their code reader only brought up the P0420 that I already knew about.

I shut the car off, then keyed to On so I could look for a blink code. IMA light stayed out, no blinking, and so I refired, and it started on the IMA.

Drove about a km or two down the street, and the car stalled and IMA light came back. Tried to re-key, and it attempted (unsuccessfully) to start on the 12V. Seeing that failure, and as I was at a downhill traffic light, I bump started and continued on my way.

Got to my destination. Shut off, attempted to refire, and successfully started on 12V, but no IMA light.

Any ideas? I have the car loaded up with stuff for a show, the vents are clear, but have stuff near them, and the car was very hot when we got in. Could it be cell overheating? I don't know what to do. I have 4+ hours of driving to do before Sunday night. I'm worried the DC-DC isn't running with the IMA light on, and thus running the car is going to kill the 12V and then I'll be stranded. Anybody know for sure?

[racer26]

The car is blinking out the following codes:

IMA light: 12
EPS light: 22/23
CEL light: 67/69

Can anybody give an idea what these mean, asap?

[Eli]

The 12V battery light on the dash will come on if the DC-DC isn't charging. It sounds like you're OK. Just watch for it.

P1575-12 is MDM Voltage problem.

P0420-67 is Catalyst Efficiency
P1600-69 is IMA system malfunction, related to the P1575-12.

Kinda an odd error. Not sure what would be causing it? Has the battery been behaving otherwise?

[racer26]

It came on briefly, and went away.

I knew about the p0420.

Battery seems to have been otherwise behaving, runs up and down thru the whole scale on dash. The odd recal I think, but not frequently.

Any ideas?

Also, what connector do I need to unplug to get dc-dc on with a dead ima in case it comes to that?

[Eli]

Disconnect all three BCM connectors and it will keep the DC-DC on.

[racer26]

Ok. So I'm home now, for a short while.

the code is P1576-12 (MDM Voltage Problem).

According to the advanced DTC troubleshooting manuals, posted here, That means that the VPIN (PDU voltage), minus the VES (high battery sensor voltage) = >10V for >2 seconds.

Said manuals don't give a whole lot of insight beyond that into where to start looking. I'm assuming this is going to involve going into the IPU to fix. Sounds to me like the MDM has lost a ground, or something is shorting out, or the MDM's VES connection has come loose, and gone floating or gone high resistance.

Anybody else have ideas?

[racer26]

Also, on the way home for about 2km, the car was doing something odd, where it felt like it was surging (like the IMA motor was grabbing and releasing), and it became very difficult for me to maintain highway speed. Dunno if this helps anybody diagnose.

[racer26]

Eli and I attempted troubleshooting my car on Sunday.

We suspect the 100A fuse in the IPU (attached to the drivers side of the HV battery unit) to be the culprit.

I'm trying to find a good way to check this for sure without first extracting the battery from the car. Based on page 32-6 of the electrical troubleshooting manual, it looks as though I could check this at the red/wht wires going into the rearward edge of the MCM.

I believe with the switch in the On position, if the fuse is intact, there should be some non-zero voltage across those pins (multimeter on DCVolts setting), while if the fuse is blown, there should be 0V across them.

Would I need to disconnect the 20 pin connector C from the BCM and the 8 pin connector including these 2 wires from the MCM to ensure no other circuit paths?

[Hybrid-Battery-Repair]

Originally Posted by racer26

Eli and I attempted troubleshooting my car on Sunday.

We suspect the 100A fuse in the IPU (attached to the drivers side of the HV battery unit) to be the culprit.

I'm trying to find a good way to check this for sure without first extracting the battery from the car. Based on page 32-6 of the electrical troubleshooting manual, it looks as though I could check this at the red/wht wires going into the rearward edge of the MCM.

I believe with the switch in the On position, if the fuse is intact, there should be some non-zero voltage across those pins (multimeter on DCVolts setting), while if the fuse is blown, there should be 0V across them.

Would I need to disconnect the 20 pin connector C from the BCM and the 8 pin connector including these 2 wires from the MCM to ensure no other circuit paths?

The 100A fuse in the battery can be tested by checking voltage from the negative battery terminal to the battery side (lower side) of the HV contactor. This is where most grid chargers attach. If the fuse is blown, there will be no power from the battery. The fuse is connected between the 9th and 10 sticks with the circuit breaker.

BTW, we sell fuses.

[racer26]

Yeah Ron, can I get you to send me one of those fuses? PM me details.