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Tricky problem

10K views 83 replies 9 participants last post by  oldmansan 
#1 ·
2005 Lotus Elise

Ok so I will try to be very descriptive here, I am at a complete loss. So a friend of mine replaced my old battery with an AGM while I was deployed, when I took a turn the battery fell out of the harness (I should have checked it) and slid across the trunk pretty violently. I secured the battery and never had the problem again.

2 years later now, I started having an issue where the solenoid would engage once, all power would die to the vehicle, and I would have to get out and jiggle the wire a bit and it would start. Now the battery is NOT charging while running (at least not topping off and it seems to drop below 75% relatively quickly), there is NO solenoid engagement, the fuel pump DOES prime, the car CAN be push started, everything inside is operable full force, no fuses are blown (I switched all starter fuses in front and back), the battery checked good at Auto Zone but the charge was below 20%, and the alternator runs the vehicle flawlessly for 3+ hours.

I thought at first it was a bad solenoid but after push starting the car or jumping the battery on a charger it would engage and start even after it was shut down which made me think the solenoid was locked into the starter but I can rock it in 6th and turn the motor just fine. If the car sat for a while, it would not start again. I charged the battery over night on 2A and it started up like a champ and ran for a whole day, but now even charging the battery will not engage the solenoid, nor will the 50A jumper on the battery charger.

I cut off a bit of the ground wire because of corrosion and realized it was pretty green even after the 8 inches I cut off, and also at the chassis but the exposed wire running to the engine block is fine. I can't get to the starter, honsetly can't even find it from below or above so maybe it is a connection at the starter, but man it is hidden.

I am trying not to replace the MFRU and ECU just to find out it was a cable connection, so I would really appreciate your help with this one. I searched the forum and found only one post that was close and there was never any response from the OP.

I had this problem happen today and after turning the key about 5 times the immobilizer light started flashing and the vehicle started...I read from SirLotus that this indicated a bad connection. I cleaned all terminals and put in new clamps on the battery..Any help you guys can offer will be greatly appreciated. I am great with old cars, but all this electrical stuff is far beyond me....Thanks guys.

Brad
 
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#4 ·
Ok I ran everything. The battery not started is at 12.6 off the charger, with the car running it is fluctuating between 14.06 and 14.07, but I had to push start it, still not even a hint of a solenoid activation. Could it be a short at the solenoid? If so is there a way to get to the starter without removing the back clam? Thanks again man, you really are my hero right now.
 
#3 ·
Ran the charger on 2A for about 4 hours and it said the battery was topped off again, yet it only ready 12.6v with the vehicle not running, and this was right after disconnecting the battery from the charger. I know that there is a charge that floats on top after a start or charge so I am thinking the battery may be bad? A friend is spotting me one of his agms to try it out, but now the problem is: Why have I killed 2 AGM red tops in the last 4 years? I will let you know what the outcome is, but the vehicle still would not turn over with the 12.6. It also showed some signs of low voltage for the first time since the problem started; dimming lights and failing relays.

Any idea what could cause this? Still not sure the car will start with the new battery, I will post in about 5m to let you know. Thanks again, you are the man.
 
#7 ·
Thanks again for responding guys. There is no draw on the battery voltage at all when pressing the starter button but this morning, (with key turned to acc) the battery volt was around 12.05....Could something be causing parasitic draw? Everything is off in the vehicle, even the blower at this point.

Also, I changed the battery out last night with another, still nothing, even with the 50A jumper on the other battery it would not start.
 
#12 ·
Thanks a ton man, I finally got to it, but all I have is a hydro jack and 2 stands which makes this a pretty tough situation with so little space. I am getting 12.1 at the solenoid using the block as a ground, is that ok? Also you said remove the little wire, but the only little wire I see is a clip near the main hot to the solenoid, is that the one you are talking about? If so this may become quite a project, there is not nearly enough space with my setup to get that clip figured out and pulled apart. I tried for a bit but no luck.
 
#13 ·
It was not flashing until I turned the key maybe 5 or 6 times and after it started flashing the vehicle started. It flashed for about maybe 30sec after ignition and extinguished. Having a bit of trouble getting to all the wires under this car at the moment, quite an exercise in patience..
 
#14 ·
Gunner,
Move away from the starter connection for now. At this point I think you have two problems. Problem number one is your battery is on the way out (Optima Batteries Suck). Problem number two is your starting issue which I don't think has anything to do with your weak battery.
There are a couple of things that could cause what you are seeing,
- a faulty push button switch in the dash
- a faulty immobilizer unit
- a faulty multi-function relay
- a faulty ECU
- a faulty starter solenoid

Given that your fuel pump runs and you can pop start the car I think you can rule out the immobilizer. A faulty ECU is also highly unlikely, the starter solenoid and push button switch are also long shots. I'm going to put my money on the multi-function relay.
 
#15 ·
Well that sounds like bad news. I have had my hands on the MFRU so I can see that with a little work I could probably replace that easily. Is there any way to test out the part to make sure that is the culprit? Thanks again you guys for helping me out with this one.
 
#16 ·
Best way is to swap with a known good relay (got any buddies local with an Elise?), only other way is to pull it and bench test it with a voltage supply/meter and the circuit schematic.
 
#17 ·
I wanted to make sure I reiterated something from earlier that may have been missed (maybe I forgot to type it) My ground coming from the batt terminal to the (chassis?) is coated in green corrosion all the way through the sleeve from terminal to chassis. Could this cause the issue?
 
#19 ·
Hi Gunner...
Not much to add here... but with your description of a "traveling" battery, I was initially thinking something to do with the cabling... Of course, I'm no Lotus mechanic, but I have to go with Smddany's recommendation. Good Luck!

Unrelated Comment: Your login credential (Gunner53) is interesting...
I was a SPECTRE Gunner and was born in '53. Please tell me it doesn't "define" you! Otherwise, you be OLD! Ha...ha.
 
#23 · (Edited)
Gunner,
The corrosion on the ground wire isn't good but it would not cause your starter solenoid not to at least "click" when you push the start button.
Current flow issues (bad grounds) usually manifest as starters that go "clack, clack, clack" when you push the button as there is enough current flow to engage the solenoid but once the contact hits for the starter it draws the voltage down so low that the starter solenoid uncouples, which then starts the cycle again.
Your situation with getting absolutely nothing when you push the button points towards the list of possible faults I have already mentioned. I continue to stand by my multi-function relay diagnosis.
 
#24 · (Edited)
Gunner,
I did the homework for you, here is a diagram of how to check your multifunction relay. When voltage is applied to pins 4 and 6 you should here a click of a relay and you should see continuity between 5 and 7. If this tests out, it's not the relay.
 

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#31 ·
So I have messed around with it a bit more, (let me know about that relay you want to sell SL). The newest addition to issues spotted is that the ECU battery fuse in the back was blown now, and also the battery when started is draining pretty rapidly (from 14.16-14.11 in about 1 minute) Any ideas?
 
#32 ·
Replace the fuse and monitor, this is a common fuse to blow when people have been screwing around with their battery (usually connecting it backwards). 14.11 volts while running is perfectly fine. Did you have to pop start again or does the starter work intermittently?
 
#33 ·
Fuse was replaced but the battery was not charging. After about 30 minutes of sitting at idle the voltage was down to around 13.4, but without the car running it was at around 12.3. I did have to pop start again, the starter wont even work intermittently anymore.
 
#34 ·
Alternator will charge at a default rate if the voltage sense circuit fuse is blown R3 (5amp), it will not charge at all if fuse R6 (7.5 amp) is blown as this provides the ignition power signal to the internal voltage regulator in the alternator. If R3 is blown it will charge but illuminate the Alt light in the dash, if R6 is blown there will be no charge or illuminated dash light.
The battery dropping down to 12.3 when the car is off tells me you have a weak cell and this is why you only see 13.4 when running (which is plenty of voltage for the ECU to operate on). 12.3 volts is basically a dead battery.
I would seriously replace the battery with a standard wet cell (properly secured) or a light weight dry cell. Have you pulled the multifunction relay to test yet?
 
#35 ·
While I agree the current battery is probably due for replacement, I'm not convinced his charging system is healthy. Throwing a battery at the problem won't solve this if the charging system isn't doing the job it's "charged" with (pun intended).

San
 
#38 ·
Heh thanks San, that is good. I may be wrong but I was always told a healthy alternator should sit around 14v give or take .3. Since mine was dropping so fast (and showed no signs of slowing down) there must be something wrong with it, which makes me agree with Sir Lotus that the MULTI function relay is the culprit. The multi part is what sells me because it seems there is more than one problem, but maybe I am stupid.
 
#50 ·
Ok just an update, I tried replacing the battery and same problem. There is two (maybe three) gentle (but loud) clicks coming from what I think is the forward bay when the key is turned to the start position (same time the pump primes). I live in Florida so my blower is always on when I turn the key so maybe I have never noticed till now. Possibly a tell for the problem? I will be working on the MFRU testing next, thanks guys.
 
#51 ·
Ok so I think I have it figured out. The solenoid (assuming the lead is the small wire with the clip) is not receiving power when the button is pressed. The fuel pump is priming and I can hear the relay for that, but no relay for the starter (if you should hear the relay). The start button is receiving power on both green wires, one black is showing as a ground due to the ohm detector, and another black wire is blank. That black wire I assume is the wire that takes the power to the solenoid when it is engaged, and when I test that wire with the button not pressed against a power I get 12v, when the button is depressed I read 0. That makes me think that the relay that controls the starter is stuck open not allowing the power to travel, and instead the power is running to the ground.
Let me know how far off I am with this.

Also the noise I was hearing is the relay in the front of the car under the driver side (left) access panel. I think it is the AC relay.

Also, last note, the MFRU is getting very hot on the driver top side, which makes me think there is a constant ground there which is causing the power drain from the battery and it not being able to keep it charged while running.

I am no McGyver, but I think this is the problem?
 
#53 ·
Gunner,
Here's an easier test that will get you a bit further. you can at least pull the MFRU and instead of applying power to the two points I direct you to in the diagram, you can at least set your meter to ohms and check resistance across the pins.This the coil and should have a value of 5-10 ohms, exact value doesn't really matter as long as its not open or has a ohm value in the mega ohm range.
One other good test would be to pull the plug from the MFRU and measure voltage on pin 7 RMC 1 of the harness when you push the start button (you may need an assistant), if there is no voltage at that point your issue lies possibly in the immobilizer unit.

Good Luck and keep us posted.
 
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