dpcgtp

iTrader: (2)

Anyone have a complete engine harness diagram for a 99-00 b16a2 civic????
I've searched and searched. Can't find one. I'm have electrical problems.

My problem is when I jump the connector at the engine coolant temp switch with ignition on The relay slots at the fuse box isn't getting any power. Used a muti meter to confirm this. But if I jump the relay slots at the fuse box the fan will come on. So that tells me there's something wrong with the wiring between the connector for the coolant temp switch and the fuse box.

tony_2018

Are you jumping the thermostat switch or the coolant temp sensor, two different sensors.

dpcgtp

iTrader: (2)

The coolant temp switch that is on the thermostat. I believe it's the only plug on the thermostat itself. (2 wire. Black&green)

Former User

Check fuses 17 and 57.

Also test the relay itself by swapping with the condenser fan relay, which I assume works.

dpcgtp

iTrader: (2)

Fuses are good and relay is good!
I'm testing the relay sockets in the fuse box under hood. Not the relay itself.
I'm getting constant power from the battery. I'm getting power from the ignition when it turn the key on.
I'm not getting anything from the thermo switch when I jump the connector.

dpcgtp

iTrader: (2)

RonJ@ht. From your diagram it looks like the thermo switch runs strait the the fuse box? With a wire t'd off and going INTO the ecu?? Am I reading that correctly?
If that's correct any idea what pin on the ecu does the thermo switch go into?

tony_2018

Check for continuity between the socket and the connector, doing this will verify which blade socket goes to the connector, next jump the connector and check for continuity from that same blade socket to ground.

dpcgtp

iTrader: (2)

I'm not getting any continuity from the thermo switch connector to any of the sockets. That's what I'm confused on. I wasn't sure if I'm missing something along the way between the fuse box sockets and connector. But from the diagram it looks like the green wire goes strait to the fuse box. But it can't. All the engine harness wires go to the ecu. None actually go strait to the fuse box.
That's why I'm confused about the wire diagrams I've seen!!!!??

Former User

The main problem seems to be that you assume the stock fan circuit diagram is wrong.

Former User

Post your troubleshooting details. Don't just say they're good.

Then the Grn wire between the relay socket and fan switch is broken.

tony_2018

Which fuse location did you check?

dpcgtp

iTrader: (2)

I checked all the fuse in both fuse boxes. Visually and with a multi meter.(continuity)
Ron you are right. I'm assuming that all the diagrams I see are wrong. What I don't understand is the diagrams show the green wire from the thermo switch connector goes straight into the fuse box? I must not be reading it incorrectly because no wireds goes directly Into the fuse box from the engine harness. The engine harness goes through the firewall and plugs into the ecu.

tech8

1. If the fan did not run when you jumped the unplugged ECT switch (fan switch) harness connector with the ignition on. Then as another test, take a long piece of spare wire and plug one end of the wire into the harness connector terminal cavity with the Green wire, then touch the other end to body ground or the negative battery terminal. Turn the ignition on, does the fan run now? If it does, then it means there may be an open (break) in the Black wire from ground G101 of the harness connector to the ECT switch (fan switch).

2. If the fan still doesn't run by jumping the Grn wire directly to ground, then start looking for an open in the Grn wire. (This is assuming the check for power sources to the relay was accurate.)

The Grn wire runs from the ECT switch through terminal no. 7 of Connector C131 (22-Grn connector located behind right kick panel) and then to terminal no. 1 of Connector C352 (9 - Gry connector attached at bottom of under-hood fuse/relay box.

Former User

The diagram I posted is correct. At this point, don't doubt it, and do your troubleshooting accordingly.

You posted conflicting troubleshooting data. At one point, you say that the relay socket doesn't get voltage. Later statements you post conflict with this statement. Clarifying this huge discrepancy is the first step to solving the problem.

The routing of the Grn wire to the ECU is irrelevant to the problem, and your focus on it is an unnecessary distraction.

dpcgtp

iTrader: (2)

Ron I'll try to clear it up.
The relay sockets is getting power from battery and ignition I jump them with a wire at the sockets and the fan turned on. confirming that it is getting power from the ignition and battery.
it's not getting the signal from the thermo connector to complete the process to throw the relay itself and kick the fan on.

dpcgtp

iTrader: (2)

Tech8. I also confirmed the black ground wire on the thermo connector was good by using a test light. Touching read lead to battery and using the black wire in the connector as the ground. The light came on. So that means the ground in the connector must be good.

tech8

On the relay, power (+) from Under-dash Fuse No. 17 and ground (-) from the ECT switch needs to be applied to the relay coil for it to energize and close the relay contact, which will then allow power (+) from under-hood Fuse No. 57 through to the radiator fan.

Normally, most people just jump the cavity terminals which goes from under-hood Fuse No. 57 to provide power directly to the fan. This would not necessarily mean there is power from under-dash Fuse No. 17 to the relay coil. Have you tested that there is power to that terminal from under-dash Fuse No. 17 with the ignition ON?

Former User

Can I assume that the fan switch connector was unplugged and jumped during these two relay jump tests?

I don't understand the actual problem here. Please clarify. The fan switch is only activated when the engine coolant reaches a specified temperature.

tony_2018

I think i know what he saying, he jumped the the blk/red wire to power the fan. The issue is looking more like there is either a connection issue with the black/yellow wire, or the green wire. I would go looking for that fuse under the dash and confirm again.

dpcgtp

iTrader: (2)

Tech8. At the radiator fan relay under the hood. I popped off the relay.
I test the relay sockets. I have a constant power in one cavity.
In another cavity With the ignition off I have no power. Turn ignition on and I have power in that cavity.
So I figured that everything pertaining to the ignition is good to that point. Am I wrong to assume that???

tony_2018

Put the relay back in, apply ground signal to the green wire from a different source.

tech8

Power to relay is good then if it is ~12 volts for those two cavity. That would leave the ground or relay in question.

dpcgtp

iTrader: (2)

Tech8. That's what I'm thinking.
There's 4 cavities were the relay plugs into. No particular order.
1-Ignition,2-battery,3-sends power to fan and the 4th one is a incoming signal from the ecu that comes from the thermo switch. ??? Is that correct???

tony_2018

Did you check for continuity from the engine fusebox to the green wire?

tech8

The radiator fan relay can be grounded through either the engine coolant temperature switch (fan switch) or the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM can independently send a ground signal to the radiator fan relay without the fan switch.